文摘
In a randomized controlled trial (RCT), 272 patients were assigned to lysine acetylsalicylate 160?mg/day (n--3) or 300?mg/day (n--7) or placebo (n--32). The primary end points were adenoma recurrence and adenomatous polyp burden (APB) at year 1 or 4 (last colonoscopy) and at year 4. At last colonoscopy, APB tended to be lower under aspirin 160?mg or at either dose compared with placebo (P--.06 and 0.07, respectively). At year 4, 55 patients had received aspirin 160?mg/d, 47,300?mg/d, and 83 placebo. APB and proportions of patients with at least one recurrent adenoma were similar in both groups. A personal history of adenomas and an initial APB higher than 10?mm predicted recurrence. Among 219 adenomas from 136 patients, 128 adenomas (58%) from 59 patients strongly expressed COX-2 assessed by immunohistochemistry, mainly adenomas larger than 10?mm (84/129 vs 44/90; P--.02) and adenomas showing high-grade dysplasia (22/29 vs 104/188; P--.04). Deep stromal initial expression of COX-2 predicted recurrence (P--.04). Protection by aspirin was mainly observed in patients in whom COX-2 initial expression was low (RR: 0.59; 95% CI--.39-.90; P--.02). Aspirin decreased adenoma recurrence significantly at 1?year, marginally at year 1 or 4, and not at year 4, possibly due to attrition but also to a differential effect according to polyp natural history. In a recent patient-level meta-analysis including the four published RCTs, aspirin significantly decreased adenoma risk by 17% and risk of advanced lesions by 28%.