Flexible sigmoidoscopy and colonoscopy

Beginning at age 50, a flexible sigmoidoscopy screening tests is recommended every three to five years. Flexible sigmoidoscopy is an exam of the rectum and the lower colon using a viewing tube (a short version of colonoscopy). Recent studies have shown that the use of screening flexible sigmoidoscopy can reduce mortality from colon cancer. This is a result of the detection of polyps or early cancers in people with no symptoms. If a polyp or cancer is found, a complete colonoscopy is recommended. The majority of colon polyps can be completely removed by colonoscopy without open surgery. Recently doctors are recommending screening colonoscopies instead of screening flexible sigmoidoscopies for healthy individuals starting at ages 50-55. Please read the Colon Cancer Screening article.

Patients with a high risk of developing colorectal cancer may undergo colonoscopies starting at earlier ages than 50. For example, patients with family history of colon cancer are recommended to start screening colonoscopies at an age 10 years before the earliest colon caner diagnosed in a first-degree relative, or five years earlier than the earliest precancerous colon polyp discovered in a first-degree relative. Patients with hereditary colon cancer syndromes such as FAP, AFAP, HNPCC, and MYH are recommended to begin colonoscopies early. The recommendations differ depending on the genetic defect, for example in FAP; colonoscopies may begin during teenage years to look for the development of colon polyps. Patients with a prior history of polyps or colon cancer may also undergo colonoscopies to exclude recurrence. Patients with a long history (greater than 10 years) of chronic ulcerative colitis have an increased risk of colon cancer, and should have regular colonoscopies to look for precancerous changes in the colon lining.

Genetic counseling and testing

Blood tests are now available to test for FAP, AFAP, MYH, and HNPCC hereditary colon cancer syndromes. Families with multiple members having colon cancers, members with multiple colon polyps, members having cancers at young ages, and having other cancers such as cancers of the ureters, uterus, duodenum, etc., should be referred for genetic counseling followed possibly by genetic testing. Genetic testing without prior counseling is discouraged because of the extensive family education that is involved and the complicated nature of interpreting the test results.

The advantages of genetic counseling followed by genetic testing include: (1) identifying family members at high risk of developing colon cancer to begin colonoscopies early; (2) identifying high risk members so that screening may begin to prevent other cancers such as ultrasound tests for uterine cancer, urine examinations for ureter cancer, and upper endoscopies for stomach and duodenal cancers; and (3) alleviating concern for members who test negative for the hereditary genetic defects.

Diet and colon cancer to prevent colon cancer

People can change their eating habits by reducing fat intake and increasing fiber (roughage) in their diet. Major sources of fat are meat, eggs, dairy products, salad dressings, and oils used in cooking. Fiber is the insoluble, nondigestible part of plant material present in fruits, vegetables, and whole-grain breads and cereals. It is postulated that high fiber in the diet leads to the creation of bulky stools which can rid the intestines of potential carcinogens. In addition, fiber leads to the more rapid transit of fecal material through the intestine, thus allowing less time for a potential carcinogen to react with the intestinal lining. For additional information, please read the Colon Cancer Prevention article.