Colon Cancer Update with The Cleveland Clinic
WebMD Live Events Transcript
March is National Colorectal Cancer Awareness Month. Cleveland Clinic colorectal
cancer specialists Carol Burke, MD, and James M. Church, BSc, MBChB, MedSci,
joined us on March 15 and answered your questions about risk factors, diagnostic
tests, the latest treatment options and more.
The opinions expressed herein are the guests' alone and have not been
reviewed by a WebMD physician. If you have questions about your health, you
should consult your personal physician. This event is meant for informational
Welcome to WebMD Live. Let's start by discussing
risk factors for colorectal cancer.
The baseline risk for Americans for developing colorectal cancer in their lifetime is approximately 6%, which is in line with other western societies, but still quite high. This means if no screening tests are done, 6 out of 100 people will get a cancer in their large bowel at sometime in their life.
The most common risk factor is a family history of colon cancer , and if you have one parent who's had a colon colorectal cancer, your risk doubles, which means 12%. If you have two close relatives with colon cancer the risk goes up five to six-fold, so that's somewhere about 30% to 35% risk of getting colon cancer in your lifetime. That's why knowing your family history of colorectal cancer is so important. The other common risk factor is having had a precancerous polyp or a colon or rectal cancer yourself in the recent past.
Dr. Church, what is the role -- if any -- of diet in colorectal cancer?
There is general agreement that our western-type diet, high in animal fats and red meat and relatively low in fruits and vegetables, is a major predisposing factor to colon and rectal cancer. This is very obvious when you look at studies such as those done in native Japanese who eat very differently than Americans, and have a very low percent of colon and rectal cancer. But, when the Japanese migrate to Hawaii or the U.S., their diet changes very quickly and their risk of colon and rectal cancer becomes the same as your average American.
Are most polyps considered precancerous?
There are several different types of polyps that occur in the colon and rectum. Only one type, the adenoma, is known to be precancerous. Adenomas are quite common -- approximately 40% of men over the age of 55 will have at least one. Only one in every 200 adenomas will turn into cancer, but we don't know which ones those will be. On the other hand, all colorectal cancers arise from an adenoma.
|"If our current generation of teenagers starts to eat more healthfully, there is every reason to suspect that when they are in their 50s and 60s their incidence of colorectal cancer will be lower than ours." |
How should we correct our diets to prevent colon cancer?
There's no evidence that short-term diet changes can reverse the tendency for polyps and cancers to form. However, if our current generation of teenagers starts to eat more healthfully, there is every reason to suspect that when they are in their 50s and 60s their incidence of colorectal cancer will be lower than ours.
Is some type of follow-up treatment in order following removal of one or more adenomas?
Yes. The risk of having more adenomas in the future, after removal of one, depends on the size and the number and the microscopic appearance of the first adenomas. Patients with more than three adenomas are at high risk of developing others and follow-up is quite short. We would recommend repeat colonoscopy one to two years later. Follow-up after removal of large adenomas is also quite short to make sure that the polyp has been completely removed.
It is known that colonoscopy will miss a significant number of adenomas. The smaller the adenoma the greater the risk of it being missed at colonoscopy; therefore, we always schedule follow-up between 3 and 5 years so that if an adenoma was missed at the original examination, it doesn't have a chance to grow too big or become malignant before it is detected.