There are many methods by which colon cancer can be diagnosed which includes barium enema, sigmoidoscopy, colonoscopy and biopsy once a mass is found.

Fecal Occult Blood Testing ( FOBT )

Other names include: Occult Blood Testing, Hemoccult^tm, Hemoquant,^tm Hemoccult Sensa^tm, Hemewipes^tm, etc.

This is a test that detects the presence of occult (detectable only by chemical means and not visible) blood in the stool. Such blood may arise from anywhere along the digestive tract but is most likely to originate in the colon.

There are many ways to collect the samples. You can catch the stool on Saran^tm wrap that is loosely placed over the toilet bowel and held in place by the toilet seat. Then put the sample in the clean container supplied or on the card which was given you. One test kit, Hemewipes ^tm, supplies a special toilet tissue that you use to collect the sample, then put the sample in a clean container. For children wearing diapers, you can line the diaper with Saran^tm wrap.

Laboratory procedures vary. In one type of test, a small sample of the stool is placed on a special paper “card”. A drop or two of testing solution is applied to a positive and negative control at the bottom of the card. A color change ( often blue ) indicates the presence of blood in the stool.

Do not consume red meat or fish ( contain non-human hemoglobin ) for 3 days as this can cause a false positive reading for blood. Discontinue drugs and substances that can interfere with the test such as: Vitamin C which can cause a false negative reading; Horse radish, fresh broccoli, turnips, cauliflower ( have vegatable peroxidase ) and colchicine which can give a false positive reading.

Flexible Sigmoidoscopy

Flexible sigmoidoscopy can reach as high as the descending colon and can be done by a trained Primary Care Physician. Sigmoidoscopy has been proven to reduce the incidence and mortality of colon cancer through early detection. Flexible sigmoidoscopy however, is not an adequate method of screening in hereditary colon cancer as 2/3 of the lesions develop proximal to the splenic flexure. In these cases colonoscopy should be used. Flexible Sigmoidoscopy ( Flex Sig ) is done without sedation usually in the practitioner’s office. Flexible sigmoidoscopy can detect about 65%­75% of polyps and 40%­65% of colorectal cancers. This test, for an investment of 3-5 minutes, can with little discomfort reduce the likelihood of your developing colon cancer and if colon cancer is present detecting it at an early, highly curable stage.

Colonoscopy

Colonoscopy remains the gold standard for visualization, biopsy and removal of colonic polyps. The removal of all polyps by colonoscopy has been demonstrated to reduce the risk of colon cancer by 76 to 90 percent. In 1994 over 2,000,000 colonoscopies were performed in the

Barium Enema

Enthusiasm for the double contrast barium enema has declined in recent years in favor of colonoscopy, despite its lower cost. The reason for this decrease in use as a diagnostic tool lies in the reduced sensitivity of this test in detecting polyps of less than 1 cm, in detecting polyps in areas where a single lumen is not detectable ( i.e. sigmoid, rectosigmoid, hepatic and splenic flexures ) and patient comfort and compliance issues. Despite these limitations, when a colonoscopy is not possible the double contrast barium enema when combined with a flexible sigmoidoscopy is an acceptable alternative, with the exception of surveillance familial polyps, familial colon cancer and inflammatory bowel disease, where attention to small details of the colonic mucosa is required and the likelihood of biopsy or polyp removal is high.

Screening for Colon CancerCurrent screening procedures suggested by the American cancer society include annual digital rectal examination beginning at age 40, annual fecal hemoccult screening starting at age 50 and sigmoidoscopy every 3-5 years beginning at age 50 for symptomatic individuals having none of the high-risk factors for colorectal carcinoma. For those with high risk factors screening should be done more often and at an earlier age depending on the risk factor involved. It is evident that better screening methods are needed as only 38% of colon cancers are localized at the time of diagnosis. If polyps are found on Flexible Sigmoidoscopy or on a Barium Enema, Colonoscopy will usually be performed to remove the polyps and to make sure that there aren’t any other undetected polyps or cancer. Screening of patients by use of carcinoembryonic antigen or CEA is not recommended because it generally rises after the tumor is large and has spread. It is not specific for colon cancer and it can rise without having a cancer in smokers.

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