Evaluation of screening tests for colorectal cancer.

The following guidelines are proposed for the asymptomatic patient representing for routine examination. Instruct the patient to eat All Bran cereal or a similar product for breakfast for three consecutive days prior to the day of appointment. At the time of appointment the stool obtained from rectal examination or from a spontaneous bowel movement is checked for occult blood using the guaiac method. If the findings are negative, no further tests are recommended. If positive, the patient is given complete dietary instructions in a non-meat, high-residue diet with avoidance of beets, horseradish, vitamins, or aspirin-containing compounds. The patient is then given six Hemoccult or Quikcult slides and is instructed to prepare two fecal slides from each stool specimen daily for three days. If these are all negative when tested, no further studies are necessary. If one or more are positive, however, sigmoidoscopic examination and colon and upper gastrointestinal radiography should be carried out in that order. Evidence that early lesions (Duke A or B) are detected and the cure rate improved with this procedure is quite convincing.