The term “genetic testing” used in this article encompasses all tests and methods thought to identify cancer or the predisposition for cancer via analyzing DNA or RNA of an organism. It can be further divided in two general groups – tests that screen host (human) DNA for mutations (genetic testing) and tests that identify the presence of parasite DNA (bacterial or viral).
One of the most useful examples of a genetic test is one that screens for parasite DNA associated with human papillomavirus (HPV). Scientific research showed that persistent HPV infections could be one of the causes of cervical cancer. In 2007, it was estimated that 11,000 women in the United States would be diagnosed with this type of cancer and nearly 4,000 would die from it. Cervical cancer affects nearly half a million women each year worldwide, claiming a quarter of a million lives. Studies also suggest that HPVs may play a role in some cancers of the anus, vulva, vagina, and penile cancer (cancer of the penis) (1). In addition, studies have found that oral HPV infection could be a risk factor for oropharyngeal cancer (cancer that forms in the middle part of the throat and includes the soft palate, the base of the tongue, and the tonsils) (1,2).
Some types of HPV are referred to as “low-risk” viruses because they rarely cause lesions that develop into cancer. HPV types that are more likely to lead to the development of cancer are referred to as “high-risk.” Both high-risk and low-risk types of HPV can cause the growth of abnormal cells, but only the high-risk types of HPV can lead to cancer. Sexually transmitted, high-risk HPVs include types 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 66, 68, and 73 (3). HPV types 16 and 18 together accompany about 70 percent of cervical cancers (3, 4).
It is important to note, though, that presence of HPV only signals of the increased risk of developing cancer, it does not detect cancer cells. The great majority of high risk HPV infections go away on their own without causing any type of abnormality. Even among the women who do develop abnormal cell changes with high-risk types of HPV, only a small percentage would develop cervical cancer if the abnormal cells were not removed. Studies suggest that whether a woman develops cervical cancer depends on a variety of factors acting together with high-risk HPVs (5). The factors that may increase the risk of cervical cancer in women with HPV infection include smoking and having many children (5).
Genetic testing is a process that looks for inherited genetic alterations that may increase the risk of certain cancers. This type of testing may show whether the risk in a family is passed through their genes. There is evidence that some kinds of cancer, such as breast and ovarian cancer, seem to run in families.
A genetic test for breast and ovarian cancer risk will not yield a simple "yes" or "no" answer. If a gene alteration is found, this will indicate that a person has an increased risk of getting cancer, but it will not tell if or when cancer will develop. If an alteration is not found, it still is no guarantee that cancer won't develop.
In recent years, several gene mutations have been discovered that were thought to increase a woman's risk of breast cancer. These alterations are most often found in genes named BRCA1 and BRCA2 (BReast CAncer Gene 1 and BReast CAncer Gene 2). Both men and women have BRCA1 and BRCA2 genes, so alterations in these genes can be passed down from either the mother or the father.
A woman with a BRCA1 or BRCA2 alteration were thought to be at higher risk for developing breast, ovarian, and other cancers than a woman without an alteration. However, not every woman who has an altered BRCA1 or BRCA2 gene will get cancer, because genes are not the only factor that affects cancer risk.
A positive test result generally indicates that a person has inherited a known harmful mutation in BRCA1 or BRCA2 and, therefore, thought to have an increased risk of developing certain cancers. However, a positive test result provides information only about a person’s risk of developing cancer. It cannot tell whether an individual will actually develop cancer or when.
Moreover, a recent report (6) published by scientists from the U.S. National Cancer Institute (NCI) suggests that DNA doesn't predict breast cancer risk much better than a questionnaire.
In theory, testing for BRCA1 or BRCA2 could allow women to make more informed choices about how often to undergo routine mammograms, for example, or, more radically, whether to take anticancer drugs like tamoxifen prophylactically. These decisions are currently made by patients, in consultation with clinicians, based on a predicted risk of cancer provided by the so-called Gail model. This model calculates a risk based on the answers to seven questions, including the age at which a woman began menstruating, the age at which she had her first child, and the number of relatives with breast cancer (6, 7)
To find out how well genetic screening measured up to the question-based Gail model, researchers pooled data from five of the studies originally used to identify the breast cancer genetic risk factors. Then they retrospectively calculated a prediction of cancer risk based on each woman's data for the 10 genetic risk factors known at the outset of the study.
They asked a very simple question: “what is the probability that a woman selected at random from the group that did go on to develop cancer would have a higher risk prediction than a randomly selected woman who did not?” For a completely useless model, the answer would be 50%; for a perfect model, the answer would be 100%. The answer for the genetic screening was 59.7%, whereas the answer for the question-based Gail model was 58%. By combining the two, the researchers were able to produce a model with a predictive power of 61.8%. But that combination didn't impact the prediction of risk, also called the score, very much for most individual patients (6, 7). Cancer epidemiologist Dr. Pharoah, who published a similar report in 2008 in New England Journal of Medicine based on just seven genetic risk factors, came to the same conclusion that genetic tests don't add a whole lot to the Gail model (8).
A recent study from Roche’s biotechnology unit in California discovered 50,000 genetic mutations associated with lung cancer (9). It is suggested that the number of genetic mutations correlates with the number of cigarettes smoked, and in this specific case smoking 3 cigarettes is associated with 1 genetic mutation. This type of analysis required costly whole genome sequencing, and provides an example of the impractical uses of genetic testing for identifying disease. With over 50,000 genetic mutations to choose from, it will be difficult for the medical to rely on this evidence.
References:
1. Parkin DM. The global health burden of infection-associated cancers in the year 2002. International Journal of Cancer 2006; 118:3030–3044.
2. D'Souza G, Kreimer AR, Viscidi R, et al. Case-control study of human papillomavirus and oropharyngeal cancer. New England Journal of Medicine 2007; 356:1944–1956.
3. Munoz N, Bosch FX, Castellsague X, et al. Against which human papillomavirus types shall we vaccinate and screen? The international perspective. International Journal of Cancer 2004;111:278–285.
4. Schiffman M, Castle PE, Jeronimo J, Rodriguez AC, Wacholder S. Human papillomavirus and cervical cancer. The Lancet 2007; 370:890–907.
5. National Cancer Institute. Future directions in epidemiologic and preventive research on human papillomaviruses and cancer. Proceedings of a workshop. Bethesda, Maryland, June 2002. Journal of the National Cancer Institute Monographs 2003; 31:1–130.
6. Wacholder, S. et al, “Performance of common genetic variants in breast-cancer risk models”, New England Journal of Medicine, 362, 11, 986-983, 2010.
7. Wogan T. “Genetic Testing for Cancer Risk Not Clinically Useful”, ScienceNOW, March 17, 2010
8. Pharoah PDP, Antoniou AC, Easton DF, Ponder BAJ “Polygenes, Risk Prediction, and Targeted Prevention of Breast Cancer”, New England Journal of Medicine, 358, 2796, June 26, 2008
9. Steenhuysen, J. “U.S. gene study reveals toll of heavy smoking”, Reuters May 26, 2010. http://www.reuters.com/article/idUSTRE64P62Z20100526
Thursday, May 27, 2010
Friday, May 14, 2010
Cancer Signs and Symptoms
Although most signs and symptoms arrive in the late stages of cancer, it is still important to know what they are and what cancers they correspond to. A doctor’s evaluation of signs and symptoms can lead to further tests or perhaps nothing at all, which can be the difference between life or death. A sign is a signal which can be seen and measured and indicate that something is not right in the body, and a symptom cannot be seen nor measured. For instance, related to colorectal cancer, blood in the stool is a sign while pain in the abdomen is a symptom.
Symptoms are noticed by the person who has them, but may not be easily seen by a physician. Having one sign or symptom may not be enough to figure out what's causing it. Sometimes, a patient's signs and symptoms still don't give the doctor enough clues to figure out the cause of an illness. Then medical tests, such as x-rays, blood tests, or a biopsy may be needed.
Cancer is a group of diseases that can cause almost any sign or symptom. The signs and symptoms will depend on where the cancer is, how big it is, and how much it affects the organs or tissues. If a cancer has spread (metastasized), signs or symptoms may appear in different parts of the body. As a cancer grows, it can begin to push on nearby organs, blood vessels, and nerves. This pressure causes some of the signs and symptoms of cancer. If the cancer is in a critical area, such as certain parts of the brain, even the smallest tumor can cause symptoms.
A cancer may also cause symptoms like fever, extreme tiredness (fatigue), or weight loss. This may be because cancer cells use up much of the body's energy supply, or they may release substances that change the way the body makes energy from food. Or the cancer may cause the immune system to react in ways that produce these symptoms. Sometimes, cancer cells release substances into the bloodstream that cause symptoms which are not usually linked to cancer. For example, some cancers of the pancreas can release substances which cause blood clots in veins of the legs. Some lung cancers make hormone-like substances that raise blood calcium levels. This affects nerves and muscles, making the person feel weak and dizzy.
There are some general signs and symptoms of cancer. But having any of these does not mean that it is cancer - many other things cause these signs and symptoms, too.
• Unexplained weight loss: Most people with cancer will lose weight at some point. When a person loses weight with no known reason, it's called an unexplained weight loss. An unexplained weight loss of 10 pounds or more may be the first sign of cancer. This happens most often with cancers of the pancreas, stomach, esophagus, or lung.
• Fever: Fever is very common with cancer, but it more often happens after cancer has spread from where it started. Almost all patients with cancer will have fever at some time, especially if the cancer or its treatment affects the immune system. This can make it harder for the body to fight infection. Less often, fever may be an early sign of cancer, such as blood cancers like leukemia or lymphoma.
• Fatigue: Fatigue is extreme tiredness that does not get better with rest. It may be an important symptom as cancer grows. It may happen early, though, in cancers like leukemia. Some colon or stomach cancers can cause blood loss. This is another way cancer can cause fatigue.
• Pain: Pain may be an early symptom with some cancers like bone cancers or testicular cancer. A headache that does not go away or get better with treatment may be a symptom of a brain tumor. Back pain can be a symptom of cancer of the colon, rectum, or ovary. Most often, pain due to cancer is a symptom of cancer that has already spread from where it started (metastasized).
• Skin changes: Along with cancers of the skin, some other cancers can cause skin symptoms or signs that can be seen. These signs and symptoms include:
o Darker looking skin (hyperpigmentation)
o Yellowish skin and eyes (jaundice)
o Reddened skin (erythema)
o Itching (pruritis)
• Excessive hair growth
o Along with the general symptoms, there are certain other common symptoms and signs which could suggest cancer. Again, there may be other causes for each of these, but it is important to see a doctor about them as soon as possible.
• Change in bowel habits or bladder function: Long-term constipation, diarrhea, or a change in the size of the stool may be a sign of colon cancer. Pain when passing urine, blood in the urine, or a change in bladder function (such as needing to pass urine more or less often than usual) could be related to bladder or prostate cancer. Report any changes in bladder or bowel function to a doctor.
• Sores that do not heal: Skin cancers may bleed and look like sores that do not heal. A long-lasting sore in the mouth could be an oral cancer. This should be dealt with right away, especially in people who smoke, chew tobacco, or often drink alcohol. Sores on the penis or vagina may either be signs of infection or an early cancer.
• White patches inside the mouth or white spots on the tongue: White patches inside the mouth and white spots on the tongue may be leukoplakia. Leukoplakia is a pre-cancerous area that is caused by frequent irritation. It is often caused by smoking or other tobacco use. People who smoke pipes or use oral or spit tobacco are at high risk for leukoplakia. If it is not treated, leukoplakia can become oral cancer.
• Unusual bleeding or discharge: Unusual bleeding can happen in early or advanced cancer. Blood in the sputum (phlegm) may be a sign of lung cancer. Blood in the stool (or a dark or black stool) could be a sign of colon or rectal cancer. Cancer of the cervix or the endometrium (lining of the uterus) can cause abnormal vaginal bleeding. Blood in the urine may be a sign of bladder or kidney cancer. A bloody discharge from the nipple may be a sign of breast cancer.
• Thickening or lump in the breast or other parts of the body: Many cancers can be felt through the skin. These cancers occur mostly in the breast, testicle, lymph nodes (glands), and the soft tissues of the body. A lump or thickening may be an early or late sign of cancer and should be reported to a doctor, especially if you've just found it or notice it has grown in size.
• Indigestion or trouble swallowing: Indigestion or swallowing problems may be signs of cancer of the esophagus (the swallowing tube that goes to the stomach), stomach, or pharynx (throat). But like most symptoms on this list, they are most often caused by something other than cancer.
• Recent change in a wart or mole or any new skin change: Any wart, mole, or freckle that changes color, size, or shape, or that loses its sharp border should be seen by a doctor right away. Any other skin changes should be reported, too. A skin change may be a melanoma which, if found early, can be treated successfully.
• Nagging cough or hoarseness: A cough that does not go away may be a sign of lung cancer. Hoarseness can be a sign of cancer of the voice box (larynx) or thyroid gland.
• The signs and symptoms listed above are the ones more commonly seen with cancer, but there are many others that are less common and are not listed here.
But sometimes cancer starts in places where it will not cause any symptoms until it has grown quite large. One example is cancers in the pancreas. They usually do not cause symptoms until they grow large enough to press on nearby nerves or organs (this causes back or belly pain). Others grow around the bile duct and block the flow of bile. This causes the eyes and skin to look yellow (jaundice). By the time a pancreatic cancer causes these signs or symptoms, it is usually in an advanced stage. This means it has grown and spread beyond the place it started -- the pancreas.
Another good example of the importance of finding cancer early is melanoma skin cancer. It can be easy to remove if it has not grown deep into the skin. The 5-year survival rate (percentage of people who live at least 5 years after diagnosis) at this stage is nearly 100%. Once melanoma has spread to other parts of the body, the 5-year survival rate drops below 20%.
While colorectal cancer is often found after symptoms appear, most people with early colon or rectal cancer have no symptoms. Symptoms usually appear only with more advanced disease. This is why getting the screening tests before any symptoms develop is so important. Screening for colorectal cancer may find it at an earlier stage, when it is more likely to be curable. Screening tests can also help prevent cancer by finding polyps that can be removed before they become cancerous.
Early detection of lung cancer is critical for improving survival of this disease because only 15% of lung cancers are found when they are localized. Since there are few or no symptoms in the early stages of the disease, the majority of lung cancers are diagnosed in the late stages of the disease. Symptoms of later-stage disease may include a persistent cough, sputum streaked with blood, chest pain, voice change, and recurrent pneumonia or bronchitis. Treatment at early stages of cancer can lead to more treatment options, less invasive surgery, and a higher survival rate. For example, in recent years, the five-year survival rate of persons whose cancers were diagnosed when they were still localized (had not spread) was almost 50%. This drops to 2% for persons whose cancers were diagnosed after their cancers had spread distantly.
If prostate cancer is found during screening, it will likely be at an early, more treatable stage than if no screening were done.
Breast cancers that are found because they are causing symptoms tend to be larger and are more likely to have already spread beyond the breast. In contrast, breast cancers found during screening are more likely to be smaller and still confined to the breast. The size of a breast cancer and how far it has spread are some of the most important factors in predicting the prognosis (outlook) of a woman with this disease. Most doctors feel that early detection tests for breast cancer save many thousands of lives each year, and that many more lives could be saved if even more women and their health care providers took advantage of these tests.
Use of symptoms to trigger medical evaluation for ovarian cancer may not greatly increase early detection of ovarian cancer, and would result in a diagnosis of ovarian cancer in only 1 out of 100 women with symptoms. These results were published in the Journal of the National Cancer Institute (3). One of the reasons that ovarian cancer tends to be so deadly is that it is often detected at a late stage when it is difficult to treat. Therefore it is crucial to employ the effective screening tests that will allow for the earlier detection of ovarian cancer.
Treatment works best when cancer is found early. Finding cancer early usually means it can be treated while it is still small and is less likely to have spread to other parts of the body. This often means a better chance for a cure, especially if the cancer can be removed with surgery. The American Cancer Society and other health groups recommend cancer-related check-ups and certain tests for people even though they have no symptoms. This helps find certain cancers early, before symptoms start.
This article is brought to you by GenWay Biotech Inc. GenWay offers a cancer assessment aimed to detect 20 different types of cancer in the early stages under the brand name You Test You™, www.youtestyou.com.
References: All the data in this article are provided by the American Cancer Society.
1. American Cancer Society. 2010
2. American Cancer Society. Cancer Facts & Figures 2009. Atlanta: American Cancer Society, 2009
3. Cass I, Karlan BY. Ovarian cancer symptoms speak out—but what are they saying? Journal of the National Cancer Institute [early online publication]. January 28, 2010
Symptoms are noticed by the person who has them, but may not be easily seen by a physician. Having one sign or symptom may not be enough to figure out what's causing it. Sometimes, a patient's signs and symptoms still don't give the doctor enough clues to figure out the cause of an illness. Then medical tests, such as x-rays, blood tests, or a biopsy may be needed.
Cancer is a group of diseases that can cause almost any sign or symptom. The signs and symptoms will depend on where the cancer is, how big it is, and how much it affects the organs or tissues. If a cancer has spread (metastasized), signs or symptoms may appear in different parts of the body. As a cancer grows, it can begin to push on nearby organs, blood vessels, and nerves. This pressure causes some of the signs and symptoms of cancer. If the cancer is in a critical area, such as certain parts of the brain, even the smallest tumor can cause symptoms.
A cancer may also cause symptoms like fever, extreme tiredness (fatigue), or weight loss. This may be because cancer cells use up much of the body's energy supply, or they may release substances that change the way the body makes energy from food. Or the cancer may cause the immune system to react in ways that produce these symptoms. Sometimes, cancer cells release substances into the bloodstream that cause symptoms which are not usually linked to cancer. For example, some cancers of the pancreas can release substances which cause blood clots in veins of the legs. Some lung cancers make hormone-like substances that raise blood calcium levels. This affects nerves and muscles, making the person feel weak and dizzy.
There are some general signs and symptoms of cancer. But having any of these does not mean that it is cancer - many other things cause these signs and symptoms, too.
• Unexplained weight loss: Most people with cancer will lose weight at some point. When a person loses weight with no known reason, it's called an unexplained weight loss. An unexplained weight loss of 10 pounds or more may be the first sign of cancer. This happens most often with cancers of the pancreas, stomach, esophagus, or lung.
• Fever: Fever is very common with cancer, but it more often happens after cancer has spread from where it started. Almost all patients with cancer will have fever at some time, especially if the cancer or its treatment affects the immune system. This can make it harder for the body to fight infection. Less often, fever may be an early sign of cancer, such as blood cancers like leukemia or lymphoma.
• Fatigue: Fatigue is extreme tiredness that does not get better with rest. It may be an important symptom as cancer grows. It may happen early, though, in cancers like leukemia. Some colon or stomach cancers can cause blood loss. This is another way cancer can cause fatigue.
• Pain: Pain may be an early symptom with some cancers like bone cancers or testicular cancer. A headache that does not go away or get better with treatment may be a symptom of a brain tumor. Back pain can be a symptom of cancer of the colon, rectum, or ovary. Most often, pain due to cancer is a symptom of cancer that has already spread from where it started (metastasized).
• Skin changes: Along with cancers of the skin, some other cancers can cause skin symptoms or signs that can be seen. These signs and symptoms include:
o Darker looking skin (hyperpigmentation)
o Yellowish skin and eyes (jaundice)
o Reddened skin (erythema)
o Itching (pruritis)
• Excessive hair growth
o Along with the general symptoms, there are certain other common symptoms and signs which could suggest cancer. Again, there may be other causes for each of these, but it is important to see a doctor about them as soon as possible.
• Change in bowel habits or bladder function: Long-term constipation, diarrhea, or a change in the size of the stool may be a sign of colon cancer. Pain when passing urine, blood in the urine, or a change in bladder function (such as needing to pass urine more or less often than usual) could be related to bladder or prostate cancer. Report any changes in bladder or bowel function to a doctor.
• Sores that do not heal: Skin cancers may bleed and look like sores that do not heal. A long-lasting sore in the mouth could be an oral cancer. This should be dealt with right away, especially in people who smoke, chew tobacco, or often drink alcohol. Sores on the penis or vagina may either be signs of infection or an early cancer.
• White patches inside the mouth or white spots on the tongue: White patches inside the mouth and white spots on the tongue may be leukoplakia. Leukoplakia is a pre-cancerous area that is caused by frequent irritation. It is often caused by smoking or other tobacco use. People who smoke pipes or use oral or spit tobacco are at high risk for leukoplakia. If it is not treated, leukoplakia can become oral cancer.
• Unusual bleeding or discharge: Unusual bleeding can happen in early or advanced cancer. Blood in the sputum (phlegm) may be a sign of lung cancer. Blood in the stool (or a dark or black stool) could be a sign of colon or rectal cancer. Cancer of the cervix or the endometrium (lining of the uterus) can cause abnormal vaginal bleeding. Blood in the urine may be a sign of bladder or kidney cancer. A bloody discharge from the nipple may be a sign of breast cancer.
• Thickening or lump in the breast or other parts of the body: Many cancers can be felt through the skin. These cancers occur mostly in the breast, testicle, lymph nodes (glands), and the soft tissues of the body. A lump or thickening may be an early or late sign of cancer and should be reported to a doctor, especially if you've just found it or notice it has grown in size.
• Indigestion or trouble swallowing: Indigestion or swallowing problems may be signs of cancer of the esophagus (the swallowing tube that goes to the stomach), stomach, or pharynx (throat). But like most symptoms on this list, they are most often caused by something other than cancer.
• Recent change in a wart or mole or any new skin change: Any wart, mole, or freckle that changes color, size, or shape, or that loses its sharp border should be seen by a doctor right away. Any other skin changes should be reported, too. A skin change may be a melanoma which, if found early, can be treated successfully.
• Nagging cough or hoarseness: A cough that does not go away may be a sign of lung cancer. Hoarseness can be a sign of cancer of the voice box (larynx) or thyroid gland.
• The signs and symptoms listed above are the ones more commonly seen with cancer, but there are many others that are less common and are not listed here.
But sometimes cancer starts in places where it will not cause any symptoms until it has grown quite large. One example is cancers in the pancreas. They usually do not cause symptoms until they grow large enough to press on nearby nerves or organs (this causes back or belly pain). Others grow around the bile duct and block the flow of bile. This causes the eyes and skin to look yellow (jaundice). By the time a pancreatic cancer causes these signs or symptoms, it is usually in an advanced stage. This means it has grown and spread beyond the place it started -- the pancreas.
Another good example of the importance of finding cancer early is melanoma skin cancer. It can be easy to remove if it has not grown deep into the skin. The 5-year survival rate (percentage of people who live at least 5 years after diagnosis) at this stage is nearly 100%. Once melanoma has spread to other parts of the body, the 5-year survival rate drops below 20%.
While colorectal cancer is often found after symptoms appear, most people with early colon or rectal cancer have no symptoms. Symptoms usually appear only with more advanced disease. This is why getting the screening tests before any symptoms develop is so important. Screening for colorectal cancer may find it at an earlier stage, when it is more likely to be curable. Screening tests can also help prevent cancer by finding polyps that can be removed before they become cancerous.
Early detection of lung cancer is critical for improving survival of this disease because only 15% of lung cancers are found when they are localized. Since there are few or no symptoms in the early stages of the disease, the majority of lung cancers are diagnosed in the late stages of the disease. Symptoms of later-stage disease may include a persistent cough, sputum streaked with blood, chest pain, voice change, and recurrent pneumonia or bronchitis. Treatment at early stages of cancer can lead to more treatment options, less invasive surgery, and a higher survival rate. For example, in recent years, the five-year survival rate of persons whose cancers were diagnosed when they were still localized (had not spread) was almost 50%. This drops to 2% for persons whose cancers were diagnosed after their cancers had spread distantly.
If prostate cancer is found during screening, it will likely be at an early, more treatable stage than if no screening were done.
Breast cancers that are found because they are causing symptoms tend to be larger and are more likely to have already spread beyond the breast. In contrast, breast cancers found during screening are more likely to be smaller and still confined to the breast. The size of a breast cancer and how far it has spread are some of the most important factors in predicting the prognosis (outlook) of a woman with this disease. Most doctors feel that early detection tests for breast cancer save many thousands of lives each year, and that many more lives could be saved if even more women and their health care providers took advantage of these tests.
Use of symptoms to trigger medical evaluation for ovarian cancer may not greatly increase early detection of ovarian cancer, and would result in a diagnosis of ovarian cancer in only 1 out of 100 women with symptoms. These results were published in the Journal of the National Cancer Institute (3). One of the reasons that ovarian cancer tends to be so deadly is that it is often detected at a late stage when it is difficult to treat. Therefore it is crucial to employ the effective screening tests that will allow for the earlier detection of ovarian cancer.
Treatment works best when cancer is found early. Finding cancer early usually means it can be treated while it is still small and is less likely to have spread to other parts of the body. This often means a better chance for a cure, especially if the cancer can be removed with surgery. The American Cancer Society and other health groups recommend cancer-related check-ups and certain tests for people even though they have no symptoms. This helps find certain cancers early, before symptoms start.
This article is brought to you by GenWay Biotech Inc. GenWay offers a cancer assessment aimed to detect 20 different types of cancer in the early stages under the brand name You Test You™, www.youtestyou.com.
References: All the data in this article are provided by the American Cancer Society.
1. American Cancer Society. 2010
2. American Cancer Society. Cancer Facts & Figures 2009. Atlanta: American Cancer Society, 2009
3. Cass I, Karlan BY. Ovarian cancer symptoms speak out—but what are they saying? Journal of the National Cancer Institute [early online publication]. January 28, 2010
Thursday, May 6, 2010
What are Cancer Clusters?
A cancer cluster is defined as a greater than expected number of cancer cases that occurs within a group of people, in a geographic area, or over a period of time. A cancer cluster is a statistical event, which may or may not have a cause other than chance. There are other cancer clusters that occur without any obvious source of carcinogens.
From 1961 to 1982, Centers for Disease Control and Prevention (CDC) investigated 108 reported cancer clusters in 29 states and 5 foreign countries (1). The studies were begun in hopes of identifying a viral cause of cancer clusters. During these investigations, however, no clear cause was determined for any of the reported clusters.
Cancer cluster investigations are complex and difficult for several reasons. Although any cancer case is one too many, suspected cancer clusters often do not contain enough cases for investigators to do a meaningful statistical analysis or reach a conclusion. Determining the cause of cancer is complicated because exposure to cancer-causing agents may have occurred many years before diagnosis. Therefore, assessing the amount and type of cancer-causing agents an individual has been exposed to is difficult. Unfortunately, cancer is often the result of a combination of agents and risk factors that interact in a way that science does not yet fully understand (2).
Below is the short list of cancer clusters in the United States that were thoroughly studied by epidemiologic investigations.
1963-1999, 56 people affected by lung cancer or mesothelioma in Libby, Montana. Suspected cause tremolite. (3).
1967-1973, 4 people affected by liver angiosarcoma in Louisville, Kentucky (4). Suspected cause vinyl chloride monomer (4).
1968-1995, 103 people affected by leukemia or lymphoma in Camp Lejeune, North Carolina. Suspected cause trichloroethylene (5).
1973-1982, 16-29 people affected by brain or CNS cancer in Cooke County, Texas. The cause is still unknown (6).
1979-1996, 40 people affected by brain or CNS cancer in Toms River, New Jersey. Suspected cause SAN trimer, styrene, acrylonitrile (7).
1981-1986, 21 people affected by leukemia in Woburn, Massachusetts, (21). Suspected cause: chloroform, tetrachloroethylene, trichloroethylene, 1,2-dichloroethene, arsenic (8).
1987-1999, 20 people affected by brain cancer, leukemia or lymphoma in Wilmington, Massachusetts. Suspected cause N-nitrosodimethylamine (9).
Two recent studies deserve more attention as they shed light on another factor that may be partially responsible for the occurrence of cancer clusters.
From 1997 to 2001, doctors in Churchill County found that 15 children had leukemia. This number was higher than usual. Beginning in 2002, the Nevada State Health Division and the Centers for Disease Control and Prevention (CDC) worked together to try to learn why so many children in Churchill County were getting sick. One test found that people who lived in Churchill County had higher amounts of two chemicals in their blood and urine than did people from other areas. The two chemicals were tungsten and arsenic. However, the higher amounts were found in children with leukemia and in children without leukemia (10, 11).
Another cluster was indentified in Sierra Vista, Arizona, where from 1995 to 2003, 11 children in were diagnosed with leukemia. Because this number of cases was higher than expected, the Arizona Department of Health Services and the Cochise County Health Department asked the Centers for Disease Control and Prevention (CDC) to help them try to learn why these children got sick. CDC’s National Center for Environmental Health tested blood and urine samples from some people in Sierra Vista to measure levels of chemicals in their bodies. The results of the study showed that levels of chemicals found in most study participants were lower than levels in the U.S. population. The levels of chemicals were not different between case and comparison families (12).
However, in both studies CDC scientists found a variation in a gene called SUOX. All of the children with leukemia had this variation in the SUOX gene, and almost half of the children who did not have leukemia had that same variation. This means that even if the variation in the SUOX gene adds to the risk for leukemia, it has to be noted that there must also be other factors involved. The direct cause of most leukemias still remains unknown, and scientists are still are not sure why so many children in both cancer clusters got leukemia (10, 11, 12).
Although no clear cause was reported for any of the cancer cluster, scientists documented 15 most commonly used environmental exposure terms found in articles pertaining to cancer clusters published in U.S. newspapers from 1977 to 2001 (13).
Disease clusters continue to concern the public, and public sentiment that environmental causes are responsible and must be investigated is widely prevalent. More than thirty years ago, the Centers for Disease Control and Prevention (CDC) recognized the need to develop operating procedures for response to public concern about disease clusters. In 1990 CDC released the “Guidelines for Investigating Clusters of Health Events” (14) in which a four-stage process was presented: a) an initial response to gather source information, b) an assessment of the occurrence of the health event, c) a feasibility study, and d) an epidemiologic investigation. During the last years, these guidelines have provided a framework that most state health departments have adopted, modifying it for their specific situations and available resources.
The states have the primary responsibility for response to cancer cluster concerns within their domain. State and local health departments respond to cancer cluster reports and inquiries about suspected clusters. Most state health departments’ strategies for cluster response are based on CDC’s “Guidelines for Investigating Clusters of Health Events” with some modifications. Usually, a local or state health department starts by gathering information about the suspected cancer cluster including expected cancer rate, types of cancer, number of cases, and the age, sex, race, address, occupation, and age at diagnosis of the individuals with cancer. Information may be verified by contacting patients and relatives or by obtaining medical records. This information is then compared to census data and state cancer registry data to determine if there is a higher than expected number of cases. Most investigations do not proceed beyond evaluation of the gathered information; however the local or state health department may perform a more intensive assessment or comprehensive epidemiological study. The decision to proceed to a more intensive investigation is usually based on a set of rules developed by the health department.
National Center for Environmental Health (NCEH) of CDC becomes involved when state health departments request assistance. NCEH response has ranged from consultation with appropriate staff to active participation in an epidemiologic or biosampling investigation. In some cases, NCEH has provided assistance by conducting analysis of biological samples and storing them for future study, as it did in the childhood leukemia clusters in Churchill County, Nevada and Sierra Vista, Arizona (11, 12).
This article is brought to you by GenWay Biotech Inc. GenWay offers a cancer assessment aimed to detect 20 different types of cancer in the early stages under the brand name You Test You™. To learn more, please visit the website www.youtestyou.com.
References:
1. Caldwell GG. Twenty-two years of cancer cluster investigations at the Centers for Disease Control. Am J Epidemiol 1990; 132[1]:S43-S47
2. CDC
3. McDonald, JC. Harris, J. Armstrong, B. (2004). Occupational and Environmental Medicine 61 (4), 363–366.
4. Centers for Disease Control and Prevention, Morbidity and Mortality Weekly Report. (Feb. 7, 1997). Epidemiologic Notes and Reports Angiosarcoma of the Liver Among Polyvinyl Chloride Workers -- Kentucky. 46 (5), 97–101.
5. US Department of Health and Human Services, Agency for Toxic Substances and Disease Registry (ATSDR). (Jul. 2003). Survey of Childhood Cancers and Birth Defects at USMC Camp Lejeune. Retrieved Jan. 31, 2005
6. Centers for Disease Control and Prevention, Morbidity and Mortality Weekly Report. (August 24, 1984). Brain Cancer -- Texas 33 (33), 477–479.
7. New Jersey Department of Health and Senior Services, Hazardous Site Health Evaluation Program, Division of Epidemiology, Environmental and Occupational Health, & US Department of Health and Human Services, Agency for Toxic Substances and Disease Registry (ATSDR). (Sep. 1997). Childhood Cancer Incidence Health Consultation: A Review and Analysis of Cancer Registry Data, 1979-1995 for Dover Township (Ocean County), New Jersey
8. Costas, K. Knorr, RS. Condon, SK. (Dec. 2, 2002). A case–control study of childhood leukemia in Woburn, Massachusetts: the relationship between leukemia incidence and exposure to public drinking water. Science of The Total Environment 300 (1-3), 23–35.
9. Massachusetts Department of Public Health. (2002). Wilmington Childhood Cancer Study. Bureau of Environmental Health Assessment. Retrieved Jan. 31, 2005.
10. National Center for Environmental Health, Centers for Disease Control and Prevention. (2004). Cancer Clusters - Churchill County (Fallon), Nevada Exposure Assessment. Retrieved Jan. 31, 2005.
11. http://www.cdc.gov/nceh/clusters/fallon/genetictesting.htm
12. http://www.cdc.gov/nceh/clusters/sierravista/default.htm
13. Beverly S. Kingsley, Karen L. Schmeichel, and Carol H. Rubin.: “An Update on Cancer Cluster Activities at the Centers for Disease Control and Prevention”, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, Georgia, USA Environmental Health Perspectives • VOLUME 115 | NUMBER 1 | January 2007
14. http://www.cdc.gov/mmwr/preview/mmwrhtml/00001797.htm
From 1961 to 1982, Centers for Disease Control and Prevention (CDC) investigated 108 reported cancer clusters in 29 states and 5 foreign countries (1). The studies were begun in hopes of identifying a viral cause of cancer clusters. During these investigations, however, no clear cause was determined for any of the reported clusters.
Cancer cluster investigations are complex and difficult for several reasons. Although any cancer case is one too many, suspected cancer clusters often do not contain enough cases for investigators to do a meaningful statistical analysis or reach a conclusion. Determining the cause of cancer is complicated because exposure to cancer-causing agents may have occurred many years before diagnosis. Therefore, assessing the amount and type of cancer-causing agents an individual has been exposed to is difficult. Unfortunately, cancer is often the result of a combination of agents and risk factors that interact in a way that science does not yet fully understand (2).
Below is the short list of cancer clusters in the United States that were thoroughly studied by epidemiologic investigations.
1963-1999, 56 people affected by lung cancer or mesothelioma in Libby, Montana. Suspected cause tremolite. (3).
1967-1973, 4 people affected by liver angiosarcoma in Louisville, Kentucky (4). Suspected cause vinyl chloride monomer (4).
1968-1995, 103 people affected by leukemia or lymphoma in Camp Lejeune, North Carolina. Suspected cause trichloroethylene (5).
1973-1982, 16-29 people affected by brain or CNS cancer in Cooke County, Texas. The cause is still unknown (6).
1979-1996, 40 people affected by brain or CNS cancer in Toms River, New Jersey. Suspected cause SAN trimer, styrene, acrylonitrile (7).
1981-1986, 21 people affected by leukemia in Woburn, Massachusetts, (21). Suspected cause: chloroform, tetrachloroethylene, trichloroethylene, 1,2-dichloroethene, arsenic (8).
1987-1999, 20 people affected by brain cancer, leukemia or lymphoma in Wilmington, Massachusetts. Suspected cause N-nitrosodimethylamine (9).
Two recent studies deserve more attention as they shed light on another factor that may be partially responsible for the occurrence of cancer clusters.
From 1997 to 2001, doctors in Churchill County found that 15 children had leukemia. This number was higher than usual. Beginning in 2002, the Nevada State Health Division and the Centers for Disease Control and Prevention (CDC) worked together to try to learn why so many children in Churchill County were getting sick. One test found that people who lived in Churchill County had higher amounts of two chemicals in their blood and urine than did people from other areas. The two chemicals were tungsten and arsenic. However, the higher amounts were found in children with leukemia and in children without leukemia (10, 11).
Another cluster was indentified in Sierra Vista, Arizona, where from 1995 to 2003, 11 children in were diagnosed with leukemia. Because this number of cases was higher than expected, the Arizona Department of Health Services and the Cochise County Health Department asked the Centers for Disease Control and Prevention (CDC) to help them try to learn why these children got sick. CDC’s National Center for Environmental Health tested blood and urine samples from some people in Sierra Vista to measure levels of chemicals in their bodies. The results of the study showed that levels of chemicals found in most study participants were lower than levels in the U.S. population. The levels of chemicals were not different between case and comparison families (12).
However, in both studies CDC scientists found a variation in a gene called SUOX. All of the children with leukemia had this variation in the SUOX gene, and almost half of the children who did not have leukemia had that same variation. This means that even if the variation in the SUOX gene adds to the risk for leukemia, it has to be noted that there must also be other factors involved. The direct cause of most leukemias still remains unknown, and scientists are still are not sure why so many children in both cancer clusters got leukemia (10, 11, 12).
Although no clear cause was reported for any of the cancer cluster, scientists documented 15 most commonly used environmental exposure terms found in articles pertaining to cancer clusters published in U.S. newspapers from 1977 to 2001 (13).
Disease clusters continue to concern the public, and public sentiment that environmental causes are responsible and must be investigated is widely prevalent. More than thirty years ago, the Centers for Disease Control and Prevention (CDC) recognized the need to develop operating procedures for response to public concern about disease clusters. In 1990 CDC released the “Guidelines for Investigating Clusters of Health Events” (14) in which a four-stage process was presented: a) an initial response to gather source information, b) an assessment of the occurrence of the health event, c) a feasibility study, and d) an epidemiologic investigation. During the last years, these guidelines have provided a framework that most state health departments have adopted, modifying it for their specific situations and available resources.
The states have the primary responsibility for response to cancer cluster concerns within their domain. State and local health departments respond to cancer cluster reports and inquiries about suspected clusters. Most state health departments’ strategies for cluster response are based on CDC’s “Guidelines for Investigating Clusters of Health Events” with some modifications. Usually, a local or state health department starts by gathering information about the suspected cancer cluster including expected cancer rate, types of cancer, number of cases, and the age, sex, race, address, occupation, and age at diagnosis of the individuals with cancer. Information may be verified by contacting patients and relatives or by obtaining medical records. This information is then compared to census data and state cancer registry data to determine if there is a higher than expected number of cases. Most investigations do not proceed beyond evaluation of the gathered information; however the local or state health department may perform a more intensive assessment or comprehensive epidemiological study. The decision to proceed to a more intensive investigation is usually based on a set of rules developed by the health department.
National Center for Environmental Health (NCEH) of CDC becomes involved when state health departments request assistance. NCEH response has ranged from consultation with appropriate staff to active participation in an epidemiologic or biosampling investigation. In some cases, NCEH has provided assistance by conducting analysis of biological samples and storing them for future study, as it did in the childhood leukemia clusters in Churchill County, Nevada and Sierra Vista, Arizona (11, 12).
This article is brought to you by GenWay Biotech Inc. GenWay offers a cancer assessment aimed to detect 20 different types of cancer in the early stages under the brand name You Test You™. To learn more, please visit the website www.youtestyou.com.
References:
1. Caldwell GG. Twenty-two years of cancer cluster investigations at the Centers for Disease Control. Am J Epidemiol 1990; 132[1]:S43-S47
2. CDC
3. McDonald, JC. Harris, J. Armstrong, B. (2004). Occupational and Environmental Medicine 61 (4), 363–366.
4. Centers for Disease Control and Prevention, Morbidity and Mortality Weekly Report. (Feb. 7, 1997). Epidemiologic Notes and Reports Angiosarcoma of the Liver Among Polyvinyl Chloride Workers -- Kentucky. 46 (5), 97–101.
5. US Department of Health and Human Services, Agency for Toxic Substances and Disease Registry (ATSDR). (Jul. 2003). Survey of Childhood Cancers and Birth Defects at USMC Camp Lejeune. Retrieved Jan. 31, 2005
6. Centers for Disease Control and Prevention, Morbidity and Mortality Weekly Report. (August 24, 1984). Brain Cancer -- Texas 33 (33), 477–479.
7. New Jersey Department of Health and Senior Services, Hazardous Site Health Evaluation Program, Division of Epidemiology, Environmental and Occupational Health, & US Department of Health and Human Services, Agency for Toxic Substances and Disease Registry (ATSDR). (Sep. 1997). Childhood Cancer Incidence Health Consultation: A Review and Analysis of Cancer Registry Data, 1979-1995 for Dover Township (Ocean County), New Jersey
8. Costas, K. Knorr, RS. Condon, SK. (Dec. 2, 2002). A case–control study of childhood leukemia in Woburn, Massachusetts: the relationship between leukemia incidence and exposure to public drinking water. Science of The Total Environment 300 (1-3), 23–35.
9. Massachusetts Department of Public Health. (2002). Wilmington Childhood Cancer Study. Bureau of Environmental Health Assessment. Retrieved Jan. 31, 2005.
10. National Center for Environmental Health, Centers for Disease Control and Prevention. (2004). Cancer Clusters - Churchill County (Fallon), Nevada Exposure Assessment. Retrieved Jan. 31, 2005.
11. http://www.cdc.gov/nceh/clusters/fallon/genetictesting.htm
12. http://www.cdc.gov/nceh/clusters/sierravista/default.htm
13. Beverly S. Kingsley, Karen L. Schmeichel, and Carol H. Rubin.: “An Update on Cancer Cluster Activities at the Centers for Disease Control and Prevention”, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, Georgia, USA Environmental Health Perspectives • VOLUME 115 | NUMBER 1 | January 2007
14. http://www.cdc.gov/mmwr/preview/mmwrhtml/00001797.htm
Tuesday, May 4, 2010
Varying Survival Rates Based on Stage of Diagnosis
Survival rates are a way for doctors and patients to get a general idea of the outlook for people with a certain type and stage of cancer. Some people with cancer may want to know the survival rates for their type of cancer. Others may not find the numbers helpful, or may even not want to know them. It is up to the individual whether or not she/he wants to read about survival rates.
The 5-year survival rate refers to the percentage of patients who live at least 5 years after their cancer is found at certain stage (I-IV). Of course, some patients live much longer than 5 years. Five-year relative survival rates for non-small cell lung cancer means that people who die of other causes are not included. A staging system is a standardized way in which the cancer care team describes the extent of the cancer. Below we present relative survival rates of non-small cell and small cell lung, colon, rectal, breast and prostate cancer.
The numbers on the Chart 1 are from the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) database, based on people who were diagnosed with non-small cell lung cancer between 1988 and 2000.
*Stage IA is the earliest diagnosed stage and stage IV is the latest stage.
While these numbers provide an overall picture, keep in mind that every person's situation is unique and the statistics can't predict exactly what will happen in a certain case.
The numbers on the Chart 2 below are from the SEER database. They are based on people with small cell lung cancer between 1988 and 2001. Five-year relative survival rates (like the ones below) don't count people who died of other causes.
The numbers on the Chart 3 include people diagnosed with colon cancer who may have later died from other causes, such as heart disease. People with colon cancer tend to be older and may have other serious health conditions. This means the percentage of people surviving the colon cancer itself is likely to be higher, and many of them live much longer than 5 years.
Please note that in this study (Chart 3), survival was better for some stage IIIA than for some stage IIB. The reasons for this are not clear.
*Stage IA is the earliest diagnosed stage and stage IV is the latest stage.
In this study (Chart 4), survival was better for some stage III cancers than for some stage II cancers. The reasons for this are not clear.
*Stage IA is the earliest diagnosed stage and stage IV is the latest stage.
The numbers on Chart 5 are based on women treated a number of years ago.
The National Cancer Institute (NCI) keeps a database of survival statistics for different types of cancer. This database does not group prostate cancers by stage, but instead groups cancers into local, regional, and distant stages (Chart 6).
Local stage means that there is no sign that the cancer has spread outside of the prostate. This is like stages I and II. Almost 9 out of 10 prostate cancers are found in this early stage. If the cancer has spread from the prostate to nearby areas, it is called regional disease. This includes cancers that are stage III and the stage IV cancers that haven't spread to distant parts of the body. Distant stage includes the rest of the stage IV cancers -- all cancers that have spread to distant lymph nodes, bone, or other organs.
The 5-year relative survival rate is the percentage of men who do not die from prostate cancer within 5 years after the cancer is found. (Men with prostate cancer who die of other causes are not counted.) Of course, patients might live more than 5 years after diagnosis. These 5-year survival rates are based on men with prostate cancer first treated more than 5 years ago. Treatment has gotten better since then and for recently diagnosed patients this may result in a better outlook.
The following survival rates (Chart 7) are based on nearly 60,000 patients who were part of the 2008 AJCC Melanoma Staging Database. These are observed survival rates. They include some people diagnosed with melanoma who may have later died from other causes, such as heart disease. Therefore, the percentage of people surviving the melanoma itself may be higher.
*Stage IA is the earliest diagnosed stage and stage IV is the latest stage.
Other factors aside from stage may also affect survival. For example, stage for stage, older people generally have shorter survival times. The biggest drop begins at age 70. Although melanoma is uncommon among African Americans, when it does occur, survival times tend to be shorter than when it occurs in whites. Some studies have shown that melanoma is more serious if it occurs on a foot, palm, or nail bed. People with HIV infection and melanoma also are at greater risk of dying of their melanoma.
With recent advances in diagnostic, screening programs have more and more impact on increasing detection in earlier stages. For some types of cancer, screening can help find cancers in an early stage when they are more easily cured.
Prostate cancer can often be found early by testing the amount of prostate-specific antigen (PSA) in the blood. Another way to find prostate cancer is the digital rectal exam (DRE), in which a doctor puts a gloved finger into the rectum to feel the prostate gland. If prostate cancer is found during screening with the PSA test or DRE, cancer will likely be at an early, more treatable stage than if no screening were done. Since the use of early detection tests for prostate cancer became fairly common (about 1990), the prostate cancer death rate has dropped. Prostate cancer tends to be a slow growing cancer, so the effects of screening in these studies may become even more apparent in the coming years.
The goal of screening exams for breast cancer, such as mammograms, is to find cancers before they start to cause symptoms. Breast cancers that are found because they can be felt tend to be larger and are more likely to have already spread beyond the breast. In contrast, breast cancers found during screening exams are more likely to be small and still confined to the breast. The size of a breast cancer and how far it has spread are important factors in predicting the prognosis (survival outlook) for a woman with this disease. Most doctors feel that early detection tests for breast cancer save many thousands of lives each year, and that many more lives could be saved if even more women and their health care providers took advantage of these tests. Current evidence supporting mammograms is even stronger than in the past. In particular, recent evidence has confirmed that mammograms offer substantial benefit for women in their 40s. Women can feel confident about the benefits associated with regular mammograms for finding cancer early.
Colorectal cancer is a term used to refer to cancer that develops in the colon or the rectum. These cancers are sometimes referred to separately as colon cancer or rectal cancer, depending on where they start. In most people, colorectal cancers develop slowly over several years. Before a cancer develops, a growth of tissue or tumor usually begins as a non-cancerous polyp on the inner lining of the colon or rectum. A tumor is abnormal tissue and can be benign (not cancer) or malignant (cancer). A polyp is a benign, non-cancerous tumor. Some polyps can change into cancer, but not all do. From the time the first abnormal cells start to grow into polyps, it usually takes about 10 to 15 years for them to develop into colorectal cancer. Regular screening can, in many cases, prevent colorectal cancer altogether. This is because some polyps, or growths, can be found and removed before they have the chance to turn into cancer. Screening can also result in finding colorectal cancer early, when it is highly curable. If colorectal cancer does occur, early detection and treatment dramatically increase chances of survival.
The death rate (the number of deaths per 100,000 people per year) from colorectal cancer has been dropping for more than 20 years. There are a number of likely reasons for this. One is that polyps are being found by screening and removed before they can develop into cancers. Screening also allows more colorectal cancers to be found earlier, when the disease is easier to cure. In addition, treatment for colorectal cancer has improved over the last several years. As a result, there are now more than 1 million survivors of colorectal cancer in the United States. Regular colorectal cancer screening or testing is one of the most powerful weapons for preventing colorectal cancer.
The relative 5-year survival rate for colorectal cancer when diagnosed at an early stage before it has spread is about 90%. But only about 4 out of 10 colorectal cancers are found at that early stage. Once the cancer has spread to nearby organs or lymph nodes, the 5-year relative survival rate goes down, and if cancer has spread to distant organs (like the liver or lung) the rate is about 11%.
Not only does colorectal cancer screening save lives, but it also is cost effective. Studies have shown that the cost-effectiveness of colorectal screening is consistent with many other kinds of preventive services and is lower than some common interventions. It is much less expensive to remove a polyp during screening than to try to treat advanced colorectal cancer. With sharp cost increases possible as new treatments become standards of care, screening is likely to become even more cost effective.
Skin cancer is the most common of all cancer types. More than 1 million skin cancers are diagnosed each year in the United States. That's more than cancers of the prostate, breast, lung, colon, uterus, ovaries, and pancreas combined. The number of skin cancer cases has been going up over the past few decades. Finding possible skin cancers doesn't require any x-rays or blood tests -- just your eyes and a mirror. If skin cancer does develop, finding it early is the best way to ensure it can be treated effectively.
This article is brought to you by GenWay Biotech Inc. GenWay offers a cancer assessment aimed to detect 20 different types of cancer in the early stages under the brand name You Test You™. To learn more, please visit the website www.youtestyou.com.
References: All the data in this article are provided by the American Cancer Society.
American Cancer Society. 2010
American Cancer Society. Cancer Facts & Figures 2009. Atlanta: American Cancer Society, 2009.
The 5-year survival rate refers to the percentage of patients who live at least 5 years after their cancer is found at certain stage (I-IV). Of course, some patients live much longer than 5 years. Five-year relative survival rates for non-small cell lung cancer means that people who die of other causes are not included. A staging system is a standardized way in which the cancer care team describes the extent of the cancer. Below we present relative survival rates of non-small cell and small cell lung, colon, rectal, breast and prostate cancer.
The numbers on the Chart 1 are from the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) database, based on people who were diagnosed with non-small cell lung cancer between 1988 and 2000.
*Stage IA is the earliest diagnosed stage and stage IV is the latest stage.
While these numbers provide an overall picture, keep in mind that every person's situation is unique and the statistics can't predict exactly what will happen in a certain case.
The numbers on the Chart 2 below are from the SEER database. They are based on people with small cell lung cancer between 1988 and 2001. Five-year relative survival rates (like the ones below) don't count people who died of other causes.
The numbers on the Chart 3 include people diagnosed with colon cancer who may have later died from other causes, such as heart disease. People with colon cancer tend to be older and may have other serious health conditions. This means the percentage of people surviving the colon cancer itself is likely to be higher, and many of them live much longer than 5 years.
Please note that in this study (Chart 3), survival was better for some stage IIIA than for some stage IIB. The reasons for this are not clear.
*Stage IA is the earliest diagnosed stage and stage IV is the latest stage.
In this study (Chart 4), survival was better for some stage III cancers than for some stage II cancers. The reasons for this are not clear.
*Stage IA is the earliest diagnosed stage and stage IV is the latest stage.
The numbers on Chart 5 are based on women treated a number of years ago.
The National Cancer Institute (NCI) keeps a database of survival statistics for different types of cancer. This database does not group prostate cancers by stage, but instead groups cancers into local, regional, and distant stages (Chart 6).
Local stage means that there is no sign that the cancer has spread outside of the prostate. This is like stages I and II. Almost 9 out of 10 prostate cancers are found in this early stage. If the cancer has spread from the prostate to nearby areas, it is called regional disease. This includes cancers that are stage III and the stage IV cancers that haven't spread to distant parts of the body. Distant stage includes the rest of the stage IV cancers -- all cancers that have spread to distant lymph nodes, bone, or other organs.
The 5-year relative survival rate is the percentage of men who do not die from prostate cancer within 5 years after the cancer is found. (Men with prostate cancer who die of other causes are not counted.) Of course, patients might live more than 5 years after diagnosis. These 5-year survival rates are based on men with prostate cancer first treated more than 5 years ago. Treatment has gotten better since then and for recently diagnosed patients this may result in a better outlook.
The following survival rates (Chart 7) are based on nearly 60,000 patients who were part of the 2008 AJCC Melanoma Staging Database. These are observed survival rates. They include some people diagnosed with melanoma who may have later died from other causes, such as heart disease. Therefore, the percentage of people surviving the melanoma itself may be higher.
*Stage IA is the earliest diagnosed stage and stage IV is the latest stage.
Other factors aside from stage may also affect survival. For example, stage for stage, older people generally have shorter survival times. The biggest drop begins at age 70. Although melanoma is uncommon among African Americans, when it does occur, survival times tend to be shorter than when it occurs in whites. Some studies have shown that melanoma is more serious if it occurs on a foot, palm, or nail bed. People with HIV infection and melanoma also are at greater risk of dying of their melanoma.
With recent advances in diagnostic, screening programs have more and more impact on increasing detection in earlier stages. For some types of cancer, screening can help find cancers in an early stage when they are more easily cured.
Prostate cancer can often be found early by testing the amount of prostate-specific antigen (PSA) in the blood. Another way to find prostate cancer is the digital rectal exam (DRE), in which a doctor puts a gloved finger into the rectum to feel the prostate gland. If prostate cancer is found during screening with the PSA test or DRE, cancer will likely be at an early, more treatable stage than if no screening were done. Since the use of early detection tests for prostate cancer became fairly common (about 1990), the prostate cancer death rate has dropped. Prostate cancer tends to be a slow growing cancer, so the effects of screening in these studies may become even more apparent in the coming years.
The goal of screening exams for breast cancer, such as mammograms, is to find cancers before they start to cause symptoms. Breast cancers that are found because they can be felt tend to be larger and are more likely to have already spread beyond the breast. In contrast, breast cancers found during screening exams are more likely to be small and still confined to the breast. The size of a breast cancer and how far it has spread are important factors in predicting the prognosis (survival outlook) for a woman with this disease. Most doctors feel that early detection tests for breast cancer save many thousands of lives each year, and that many more lives could be saved if even more women and their health care providers took advantage of these tests. Current evidence supporting mammograms is even stronger than in the past. In particular, recent evidence has confirmed that mammograms offer substantial benefit for women in their 40s. Women can feel confident about the benefits associated with regular mammograms for finding cancer early.
Colorectal cancer is a term used to refer to cancer that develops in the colon or the rectum. These cancers are sometimes referred to separately as colon cancer or rectal cancer, depending on where they start. In most people, colorectal cancers develop slowly over several years. Before a cancer develops, a growth of tissue or tumor usually begins as a non-cancerous polyp on the inner lining of the colon or rectum. A tumor is abnormal tissue and can be benign (not cancer) or malignant (cancer). A polyp is a benign, non-cancerous tumor. Some polyps can change into cancer, but not all do. From the time the first abnormal cells start to grow into polyps, it usually takes about 10 to 15 years for them to develop into colorectal cancer. Regular screening can, in many cases, prevent colorectal cancer altogether. This is because some polyps, or growths, can be found and removed before they have the chance to turn into cancer. Screening can also result in finding colorectal cancer early, when it is highly curable. If colorectal cancer does occur, early detection and treatment dramatically increase chances of survival.
The death rate (the number of deaths per 100,000 people per year) from colorectal cancer has been dropping for more than 20 years. There are a number of likely reasons for this. One is that polyps are being found by screening and removed before they can develop into cancers. Screening also allows more colorectal cancers to be found earlier, when the disease is easier to cure. In addition, treatment for colorectal cancer has improved over the last several years. As a result, there are now more than 1 million survivors of colorectal cancer in the United States. Regular colorectal cancer screening or testing is one of the most powerful weapons for preventing colorectal cancer.
The relative 5-year survival rate for colorectal cancer when diagnosed at an early stage before it has spread is about 90%. But only about 4 out of 10 colorectal cancers are found at that early stage. Once the cancer has spread to nearby organs or lymph nodes, the 5-year relative survival rate goes down, and if cancer has spread to distant organs (like the liver or lung) the rate is about 11%.
Not only does colorectal cancer screening save lives, but it also is cost effective. Studies have shown that the cost-effectiveness of colorectal screening is consistent with many other kinds of preventive services and is lower than some common interventions. It is much less expensive to remove a polyp during screening than to try to treat advanced colorectal cancer. With sharp cost increases possible as new treatments become standards of care, screening is likely to become even more cost effective.
Skin cancer is the most common of all cancer types. More than 1 million skin cancers are diagnosed each year in the United States. That's more than cancers of the prostate, breast, lung, colon, uterus, ovaries, and pancreas combined. The number of skin cancer cases has been going up over the past few decades. Finding possible skin cancers doesn't require any x-rays or blood tests -- just your eyes and a mirror. If skin cancer does develop, finding it early is the best way to ensure it can be treated effectively.
This article is brought to you by GenWay Biotech Inc. GenWay offers a cancer assessment aimed to detect 20 different types of cancer in the early stages under the brand name You Test You™. To learn more, please visit the website www.youtestyou.com.
References: All the data in this article are provided by the American Cancer Society.
American Cancer Society. 2010
American Cancer Society. Cancer Facts & Figures 2009. Atlanta: American Cancer Society, 2009.
Subscribe to:
Posts (Atom)