Prospective observation of small adenomas in patients after colorectal cancer surgery through magnification chromocolonoscopy

PURPOSE: This study was designed to confirm the safety of not removing small adenoma in patients who undergo colorectal cancer surgery. METHODS: Patients who underwent surveillance colonoscopy after surgery were enrolled. The study was approved by our institutional review board. Colonoscopy was performed with magnification chromocolonoscopy. Benign adenomas of 6 mm or less in size, diagnosed based on both nonmagnified and magnified observation, were left unresected with a maximum of three polyps per patient. The sites of the polyps were marked by tattooing. Interval colonoscopy was performed predominantly yearly or biennially. Increase in size by 2 mm or larger was defined as significant. In follow-up, polyps were removed if they grew larger than 6 mm, were suspicious for high-grade dysplasia, or the patients requested to have polyps removal. RESULTS: Five hundred polyps in 284 patients met the above criteria and were not resected, and 412 polyps were followed by repeat colonoscopy. The mean observation period was 3.6 +/- 2.2 years and the mean number of repeat colonoscopy was 3.6 +/- 1.6. At the final colonoscopy, 71 percent of 412 polyps showed no change in size, 15 percent increased, 3 percent decreased, and 11 percent could not be identified. Eighty-eight polyps were resected endoscopically, and histology showed neither cancer nor adenomas with high-grade dysplasia. Two hundred fifty-five polyps detected in the same patient cohort during index/repeat colonoscopy were removed, including four adenomas with high-grade dysplasia and two T1 cancers. CONCLUSIONS: Leaving small polyps is safe even in patients who have undergone colorectal cancer surgery, provided that careful observation is guaranteed.