[Advanced adenoma in 3700 colonoscopies]

To determine the prevalence of colon polyps, distribution in the colon, as well as their histological characteristics, with special mention on advanced adenomas, in an adult population at an endoscopy center in Lima.

One year long prospective study. We obtained the demographic data, reason for procedure, and endoscopic findings of each colonoscopy. Each polyp was studied separately and its histological findings recorded.

3,701 colonoscopies were done in 3,690 patients; 1,492 (40,4%) had polyps and were included in the study. 997 (27%) had adenomatous polyps and 495 (13.4%) non adenomatous polyps. Adenomatous polyps were found throughout the colon, with a predominance of hyperplasic polyps in the rectum. 78% of the adenomatous polyps and 84% of the advanced adenomas were found in patients older than 50 years old. A total of 260 advanced adenomas were found in 203 patients (5.5%). In the advanced adenomas group, we found 62 lesions (24%) with high grade dysplasia and 12 (4.5%) with early carcinoma; as well as 37 flat lesions (14%) and 26 serrated adenomas (10%). In this group of patients, significant risk factors were: prior history of adenomas or colorectal cancer (46/203 vs. 63/495; p<0.01), and multiple adenomatous polyps found during colonoscopy (67/203 vs. 121/794; p<0.01).

Adenomatous polyps were the most frequently found polyps in our study; approximately 20% were advanced lesions, especially in patients older than 50 years old.