Doctors must always ask themselves whether a given test will do their patients any good, says Dr. Al Benson, the panel's co-chair and a medical oncologist at Northwestern University in Chicago. First, a note of caution. The new guidelines are a work in progress and should not supersede your doctor's best judgment. Nor do they apply if you are participating in a clinical trial or have been diagnosed with hereditary colon cancer. And now some background.
Colon cancer is highly curable when caught in the earliest stages.
However, most relapses, when they occur, show up within five years of the initial treatment and are usually fatal. So there's a premium on finding and treating them early. Benson and his colleagues concluded that patients should undergo a colonoscopy three years after the one that was done at the time of surgery, provided that all cancers and polyps were removed. Repeat colonoscopies are most useful for finding a new tumor unrelated to the old one. Most recurring colon cancers form elsewhere in the body, and most new cancers take time to grow.