The APACC Study is a prospected, randomized, double-blind, placebo-controlled multicentre clinical trial design to test the efficacy of regular low-dose aspirin administration in reducing the recurrence rate of colorectal adenomatous polyps. The study involved 49 gastroenterology centers from various parts of France. Patients were eligible if they had either at least 3 adenomas irrespective of size, or at least one measuring 6mm in diameter or more histologically confirmed colorectal adenomatous polyp by the local pathologist, and 2 independent pathologists, underwent a complete colonoscopy with polypectomy and were then confirmed free of polyps, were aged between 18 and 75 years at recruitment, and were be able to conform to the protocol during the study period. During a 4-week run-in period before enrolment, all subjects took 300 mg aspirin per day to test tolerance and compliance with the treatment. They were then randomized to either of the following three groups: placebo, aspirin as acetylsalicylate of lysine 160 mg/day or aspirin as acetylsalicylate of lysine 300 mg/day. Information on compliance, tolerance of the treatment and concomitant disease is obtained at regular clinical visits every 4 months. Informations on factors such as smocking habits, previous medical history was recorded at enrollment. The primary outcomes were defined as the proportion of subjects in whom at least one new adenoma was detected, and the adenomatous polyp burden calculated as the sum of the diameters of these adenomas at the follow-up colonoscopy 1 and 4 years after enrollment.