Guidelines for Surveillance Intervals after Polypectomy: Coping with the Evidence

Economically advanced countries are having trouble coping with the consequences of advancing technology. They are asking how much health care is the right amount. The factors influencing how often to do surveillance colonoscopy after polypectomy encapsulate many elements of this debate. Patients are afraid of harboring undetected cancer, and physicians are afraid of missing an opportunity to prevent cancer. The resources devoted to surveillance colonoscopy may limit access to health care for other valid indications (1–3) and leave less to spend on disease prevention, prenatal care, or elementary school education. Finally, the evidence provides little guidance on optimal surveillance frequency.

The surveillance guidelines are aimed at people who are at increased risk for advanced colorectal neoplasia (cancer and advanced adenomas) because of previously removed colorectal cancer or adenomas. On the basis of a person's findings at index colonoscopy, current guidelines stratify the risk for subsequent advanced neoplasia. They recommend colonoscopy 3 years after removal of an advanced adenoma (defined as size ≥1 cm or having villous histology or high-grade dysplasia) or 3 or more adenomas of any size and 5 to 10 years after removal of 1 or 2 nonadvanced (small tubular) adenomas (4).

These guidelines rest on a small body of evidence. Two clinical trials have compared different postpolypectomy surveillance intervals. The National Polyp Study (5), which compared 1-year and 3-year surveillance intervals, found no difference in risk for a subsequent large adenoma. The Funen Adenoma Follow-up Study (6), which compared 2-year and 4-year surveillance intervals, also found no difference in risk for new adenomas at 4 years (5.2% vs. 8.6%, which was not statistically significant). These 2 trials suggest that polyp surveillance before 3 years has little value. Case–control studies of screening sigmoidoscopy suggest that protection against cancer persists for at least 10 years and …