Colorectal cancer is deadly: it kills more Americans than any other cancer except lung cancer. When detected early, 90 percent of patients are cured of this form of cancer. Left undetected, the five year survival rate is less than 10% once it spreads beyond the colon. Unfortunately, colon screening tests are not at all popular

To allow early detection, in persons at high risk and those at average risk, several effective methods are available. Yet studies show that only about 45 percent of Americans follow screening recommendations. Cancer nearly always begins with the growth of polyps in the lining of the colon or rectum. Not all of these polyps are malignant (cancerous), and those that are may take many years to become cancerous. Effective screening involves detecting polyps and removing them. There are several methods for doing this, all of which have elements that many patients consider disagreeable.

FECAL OCCULT BLOOD TESTING (FOBT)

Fecal occult blood testing, or FOBT, takes an indirect approach by looking for bleeding related to polyps. Noticeable or “frank” blood in the stool may have many causes, including hemorrhoids. Bleeding from polyps is likely to be “occult” or hidden from view and must be detected through a laboratory test such as FOBT.

FOBT, a simple test to be performed at home, requires collecting six samples from their own stool on three consecutive days and mailing them to a laboratory for testing. Although the test is easy to perform and not invasive, most consider the collection of stool samples disagreeable. Those who perform FOBT annually have a significantly lower risk of colorectal cancer death.

Not all polyps bleed, and some bleed intermittently. False negative results are possible, thus FOBT alone will not detect all cases. False positives are also common with the test, particularly if the patient does not follow instructions. The test requires that patients avoid red meat, certain vegetables such as radishes, vitamin C, aspirin and other medications prior to testing. A recently introduced test, Hemoccult iCT, does not have these dietary and medication restrictions, therefore it is a good alternative for some.

The FOBT is a simple way to screen for problems, but the results are not definitive. In addition, since it is not invasive, the test does not allow the physician to remove the problem. If the FOBT comes back positive for occult blood, the patient is usually advised to have a colonoscopy to confirm the existence of polyps.

Another test similar to the FOBT is now available. The test can detect DNA specific to cancerous polyps. This test requires only one stool sample using a simple collection method and it requires no food or medication restrictions or preparation of the bowels. Results have been promising and the test may eventually replace the FOBT as a screening tool.

COLONOSCOPY

The most thorough examination of the colon is a colonoscopy. Also the most invasive screening method, it involves threading a scope or thin, lighted tube through the colon to examine the lining. If polyps are found, they may be removed during the same procedure, even though the majority might never become cancerous.

The preparation process for this procedure is notable for the complete bowel emptying process 24 hours prior to the test. Various medications, including enemas and laxatives are used to complete the preparation. The colonoscopy procedure also requires general anesthesia. Compared to other screening methods, colonoscopy is expensive and carries a small risk of bleeding or perforation of the bowel, usually during removal of polyps or biopsies.

FLEXIBLE SIGMOIDOSCOPY

Many physicians and patients opt for a less invasive option that uses a scope to examine only the lower half of the colon. Flexible sigmoidoscopy can be performed in a physician’s office without anesthesia. The bowels must be cleaned with enemas and laxatives in preparation.

For the person of average risk, sigmoidoscopy can be an effective screening tool, since about 80 percent of patients with cancerous polyps will have abnormalities in this part of the colon. However, like the FOBT, this method is primarily a screening test for colonoscopy since positive findings will trigger examination of the entire colon.

DOUBLE CONTRAST BARIUM ENEMA

An option for those who do not want invasive screening is a double contrast barium enema. This test involves the use of a contrast material, barium, delivered via an enema to allow x-rays of the rectum and colon. The Xray gives a doctor the ability to examine the entire colon almost as effectively as with colonoscopy. However, if polyps are found, they cannot be removed immediately as they can with colonoscopy. Any positive findings usually necessitate a colonoscopy.

Which screening tests are used depends on patient preference, resources available and individual risk factors. Only three percent of colon and rectal cancers occur in persons younger than age 40. The median age of diagnosis is 69. As a result, most doctors and medical groups recommend that screening begin at age 50 for persons of average risk.

About 10 to 15 percent of cases occur in persons with a family history of colorectal cancer or the tendency to develop numerous intestinal polyps. These individuals may be advised to start screening at an earlier age, usually through colonoscopy. If there’s a high likelihood polyps will be found, this method is the most cost effective since it allows polyps to be removed during the same procedure.

Once polyps have been found, even though they may be small, a person may require frequent colonoscopies to monitor the situation and remove polyps that appear likely to become cancerous. The biggest problem is not the effectiveness of the screening test, but the reluctance patients have to use them. “Sometimes patients agree to have sigmoidoscopy, then call in to cancel the appointment,” one doctor said. Often, the patient takes the FOBT kit but does not send back stool samples. Two newer methods now being tested are designed to address this reluctance.

IF YOU ARE 50 OR OLDER OR AT RISK…

If some or all of the available screening tests seem disagreeable to you, then you may want to talk to a cancer survivor. “Having a colostomy is disagreeable, too,” Andrew said. “If I could go back 10 years in time and start complying with screening tests, I’d do it with no complaints.” Then again, with a 10% survival rate on late diagnosis, survivors may be tough to find.

Michelle Herbert Thomas, PharmD, CDE

Clinical Director

Richmond Apothecaries, Inc.