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Mon April 2, 2012
Family History & Colon Cancer Screening
About 150,000 people develop colon or colorectal cancer each year. For about one in five, the disease is hereditary. So your family’s history with colon cancer is vital information when screening for the disease. In our KERA Health Checkup, Dr. Samir Gupta of U.T. Southwestern Medical Center tells Sam Baker your family history determines what type of screening you should have – and when.
Dr. Gupta: For about one in five patients, colon cancer is clearly a hereditary disease. For patients who have a first-degree relative with colorectal cancer, so that’s a mother, father, brother sister, or child, that the risk for colon cancer is doubled compared to the general population.
Baker: Does age matter as well?
Gupta: If the relative was younger than 50, that also is important because there are some forms of colon cancer that we call familial. And those are patients who have a general family history of colon cancer. But for about three to five percent of all colon cancer cases, there’s actually a specific inherited gene mutation that is the cause of the colon cancer.
Baker: This family history also applies to those who have relatives who have had polyps at some point?
Gupta: This is an area that we’re still learning a lot about. There’s been some evidence that having a family member who has one or more pre-cancerous colon polyps, a specific type of colon polyp called an adenoma that may be associated with an increased risk for having colorectal cancer. Our current recommendations are that if you have a first-degree relative who’s had one of these pre-cancerous polyps that you start screening at an earlier age compared to the general population.
Baker: How early are we talking about?
Gupta: In general, we would start screening someone who has a family history either at age 40 or ten years younger than the age of the family member who had colon cancer.
Baker: Can it start even earlier depending on family history?
Gupta: Yes. We have patients at UT Southwestern who need to start screening as early as age 20 or 22. Those are very specific cases where a family has been identified that has a specific inherited condition that confers a very high risk for colorectal cancer. So there are some people who have a family history that just need to have a general recommendation to start screening early, probably at age 40. But in some families we can identify a specific genetic problem -- a genetic mutation -- that means the patients need very special screening and follow-up that may need to begin as early as age 20 or even sooner in some cases.
Baker: When you say special screening --
Gupta: The most commonly done test is colonoscopy, and the second is a stool blood test. Colonoscopy is generally recommended for patients who have a family history of colorectal cancer because it is more sensitive on a one-time basis for finding colon cancers and colon polyps.
Baker: And the polyps can be removed during that process?
Gupta: That is correct. If a polyp is identified at time of a colonoscopy we generally remove the polyp.
Baker: At what point would you recommend using the other form of screening?
Gupta: Overall when it comes to colorectal cancer screening, we need to divide things into people who are at average risk for colon cancer versus those who are at increased risk, due to, for example, family history. For patients who have a family history, we generally recommend the colonoscopy test. For patients who are at average risk, the best test is the one that gets done. So both the colonoscopy and the stool blood test have certain advantages and disadvantages, and both have been shown to reduce death from colorectal cancer and also development of colon cancer.
Baker: What are symptoms of colon cancer?
Gupta: Rectal bleeding or finding blood in your stool. Another symptom can be having anemia or a low blood count, and it’s usually a specific type of anemia which is called iron deficiency anemia.
Baker: Are you likely to see those symptoms with early stages of colon cancer, or if you have simply polyps?
Gupta: No. Polyps are generally asymptomatic. So most people who have polyps don’t know they have them. That’s also the case for people who have small cancers. Generally they are not symptomatic. Many small cancers do not cause bleeding that you can actually see. It’s often not until these cancers grow larger that we see the bleeding and the anemia develop.
Dr. Samir Gupta is Assistant Professor, Division of Digestive and Liver Diseases, Department of Internal Medicine, U.T. Southwestern Medical Center.
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