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. Supported in part by Grant-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology of Japan. Read at the meeting of The American Society of Colon and Rectal Surgeons, St. Louis, Missouri, June 2 to 6, 2007.