FAMILY MEDICINE® COLUMN
By John C. Wolf, D.O.
Associate Professor of Family Medicine®
Ohio University College of Osteopathic Medicine

NEW COLON CANCER GENE TEST OF LIMITED HELP TO MOST PEOPLE

Question: I know several people that have recently found out they have colon cancer. One of them is even younger than I am (41 years old). Why is there so much colon cancer?

Answer: Your question is a very important one that researchers have been trying to answer for some time. Only lung cancer causes more deaths of U.S. citizens than colon cancer. And our modern therapy hasn't made much difference in the mortality rates for colon cancer or in the frequency with which it strikes.

Colon cancer is more common after the age of 50, but as your friend will attest, it does happen to younger individuals. A strong family history of colon cancer increases one's risk of developing the condition. This is particularly true for those with an inherited condition called polyposis coli. All individuals with this condition have colon cancer before the age of 40 unless they receive proper preventative treatment. Perhaps your friend has this condition. The specific genetic defect that causes polyposis coli has been identified and a blood test to check for the defect should be available in the next few years. This is an important step since only some people who are members of families where this condition is prevalent actually develop colon cancer. The test when available will make it possible for doctors to tell which individuals with a strong family history of colon cancer are at increased risk. However, it will not be useful as a screening test for most us who are potential colon cancer victims but don't have a family history of polyposis coli.

Colon cancer occurs more frequently to individuals living in industrialized countries. It is not clear what factors make this so. The difference in dietary habits between individuals in industrialized countries and less developed ones may be the reason for increased colon cancer. For a time, the amount of fat in the diet was proposed as the culprit, but more recent research has largely disproved this hypothesis. Low consumption of dietary fiber, high consumption of meat, low consumption of cruciferous vegetables (cabbage family) and low consumption of calcium have all been proposed as risk factors. Undoubtedly, the real reason for the increased risk of colon cancer in individuals in industrialized nations is more complex than diet alone.

Question: What are the warning signs of colon cancer?

Answer: Colon cancer is often painless and causes no change in bowel habits until the cancer is large. This is unfortunate since one's likelihood of being "cured" of colon cancer is best when the growth is small. Even though colon cancers may exist without symptoms, the following symptoms should make one think about the disease:

--bright red rectal bleeding. Most individuals immediately think their rectal bleeding is the result of simple hemorrhoids. While this is often the case, there are many other possible causes including cancer, which can itself sometimes cause hemorrhoids. So, rectal bleeding, with or without hemorrhoids, requires further testing to be sure of its cause.

--black bowel movements. Blood that enters the digestive track from any cause, including a cancer, is broken down by the action of the small and large intestines and becomes a black- colored bowel movement.

--a change in bowel movement caliber. A cancer can narrow the rectum so that the bowel movement must be small in diameter to pass.

--unexplained diarrhea that lasts for more that three days. A cancer may nearly block the colon so that stool must be liquid to pass.

--an unexplained loss in weight. A cancer often makes the individual lose weight even though he or she has made no alterations in diet or activity.

I'd recommend that you talk to your doctor about your risks for developing colon and other forms of cancer. And, in addition, everyone over the age of 50 should have a rectal examination and have their stool tested for the presence of blood once each year.

Family Medicine® is a weekly column. To submit questions, write to John C. Wolf, D.O., Ohio University College of Osteopathic Medicine, Grosvenor Hall, Athens, Ohio 45701.