Screening for Colorectoral Cancer

Cancer of the colon remains the second most prominent cause of cancer death in the United States. Survival rates may be improved by screening, as demonstrated by a 1993 study showing a 33% reduction in colorectal cancer as a result of annual screening, using the Hemoccult test.

In October 1993, a mass screening program was conducted in Houston, Texas. Almost 86,000 fecal occult blood screening test (FOBT) kits were distributed free of charge, disseminated through local media advertising; only 8293 kits were actually processed in the trial. Each person received nine FOBT kits (three each of rehydrated Hemoccult, nonhydrated Hemoccult, and Hemoccult SENSA). A video tape as well as direct verbal instruction were also provided. Patients received instructions to use dietary restrictions for two days prior to the test, not to take NSAIDs, and to limit Vitamin C to a maximum of 250 mg/d.

For both neoplasia and carcinoma, nonhydrated Hemoccult had the highest test-specific positive value. Overall, 16% of tests were positive, of which 45% (family physician provider) to 85% (gastroenterologist provider) received appropriate follow-up care as detailed by the American Cancer Society guidelines. (ACS guidelines suggest full colonoscopy, or alternatively, flexible sigmoidoscopy, plus a double-contrast barium enema, in follow-up of a positive FOBT).

The highest positive predictive value of 13.9% (nonhydrated Hemoccult), still leaves much room for improvement. Nonetheless, 23 cancers were detected, of which 87% were at an early stage. As demonstrated in this trial, equally important in reaching cancer screening goals is improved follow-up by clinicians, especially primary care clinicians.

Levin B, et al. Arch Intern Med 1997;157: 970-976.