March is colon cancer awareness month. Colon cancer is the third leading cancer diagnosis and the second leading cause of cancer death in men and women combined. About 4.5 percent of Americans will be diagnosed with colon cancer in their lifetime. Fortunately, the incidence and deaths from colon cancer have been slowly declining. The most current statistics regarding colon cancer predict that in 2016 there will be 95,270 new cases and 49,190 deaths in the United States.
Colon cancer is believed to start in abnormal glandular tissue in the wall of the colon (otherwise known as the large intestines). This tissue starts as a bulge in the colon lining and is referred to as a polyp. It is not known exactly why the abnormal tissue grows but it appears to be a nest of tissue that has a genetic flaw that causes it to grow. This seems more likely to occur if there is a genetic predisposition (family history) and may be influenced by diet. Once the polyp starts to grow, it may degenerate into cancerous tissue which then grows out of control and invades neighboring normal tissue.
Symptoms of colon cancer include blood in the stool, abdominal pain, and unexplained weight loss. These symptoms should prompt evaluation by your healthcare provider. Once symptoms are present, the chances of cure are much less than if the cancer is discovered before symptoms occur. So, the focus over the last 10- 20 years has been on early detection. If an early stage cancer or a glandular polyp can be detected and removed, the treatment success rate is very good.
Early detection can be done through screening tests. In general colon cancer is rare before age 50. The American Cancer society advises screening for colon cancer in everyone at or over 50 years of age. Screening at an earlier age may be necessary for certain individuals at high risk. The age to stop doing routine screening generally is considered to be around 75.
Testing is broken into two categories. One tests for polyps and cancer while the other screens only for cancer. Polyps and cancer can be detected by colonoscopy, flexible sigmoidoscopy, barium x-rays, or virtual colonoscopy done with a CT scan.
Colonoscopy is the preferred method of screening because it examines the entire colon and precancerous growths (polyps) can be removed. If there are no precancerous polyps found, repeat colonoscopy is recommended in 10 years. The other methods for polyp and cancer screening I mentioned are recommended every five years.
The other type of screening is testing for colon cancers by testing the stool. There are three methods including testing three stool samples for occult blood, testing one sample by a fecal immunochemical test (FIT) that specifically tests for blood from the colon, or a stool test for abnormal DNA. The advantage to the stool test is that it is not invasive, does not require bowel prep, and can be done in the privacy of one’s home. The stool occult blood and FIT tests are inexpensive but the DNA test can cost up to $800 and is not as readily available. A disadvantage to stool testing is that this screening is advised every year and if tests are positive a colonoscopy would still be the next step.
Overall, colonoscopy would be the preferred screening. Stool testing would fulfill the screening goal for those who are unable or are unwilling to do colonoscopy.
The current guidelines by the American Cancer Society can be reviewed on their website under “colon cancer screening”. Colon cancer deaths are considered to be preventable through following a regular screening program. Stay healthy my friends.
By: P. Michael Shattuck, M.D. – Community Health Network Family Physician