伦敦大学玛丽皇后学院（Queen Mary University of London）的最新研究发现，服用阿司匹林能够极大减少患上并死于消化系统主要癌症（即肠、胃和食管癌症）的风险。

针对诸多评估预防性应用阿司匹林利弊的研究和临床试验，科学家首次对所有可用证据进行了审查。顶尖癌症期刊Annals of Oncology今日公布了一项研究结论。

在伦敦大学玛丽皇后学院（Queen Mary University of London，位于英国伦敦）的癌症预防中心负责人Jack Cuzick教授的带领下，该研究团队发现服用十年阿司匹林可以降低肠癌发病率约35%，降低肠癌死亡率40%。食管癌和胃癌的患病率下降了30%，死亡率也降低了35-50%。

要获得阿司匹林带来的好处，证据显示50-65岁人群必须每日服用75-100毫克的阿司匹林，坚持至少5年以上或许10年以上。服用阿司匹林的前三年不会出现效果，只有在服用五年后才会降低死亡率。

然而，研究还警告，长期服用阿司匹林会增加消化系统出血（如胃出血）的风险。60岁人群每日服用阿司匹林，坚持十年，则消化系统出血的风险会增加2.2%-3.6%，这对很小一部分人群（少于5%）而言可能会危及生命。

整体而言，70岁以下人群发生严重或致命性胃肠道出血的几率非常小，但是70岁以后该几率会大大增加。服用阿司匹林的另一副作用体现在消化性溃疡上，发生消化性溃疡的几率增加了30%-60%。

研究还发现无法确定将阿司匹林利弊比最大化的最适当服用剂量，不同的临床试验和研究采用的剂量区间为75毫克~325毫克。并且，服用阿司匹林超过十年是否会带来更多好处，这一点尚不明确。

Jack Cuzick教授评论：“人们早就知道阿司匹林作为市场上最便宜、最常见的药物之一，可以防止患上某些类型的癌症。但是在我们此次对所有可用证据进行分析研究之前，人们并不了解服用阿司匹林是否利大于弊。

“虽然有一些不容忽视的严重副作用，但是每日服用阿司匹林看起来是戒烟和减肥之外减少癌症患病率的最佳方案，并且可能更容易实施。”

“我们的研究显示，50-65岁的人群每日服用阿司匹林，坚持至少十年，则癌症、中风和心脏病的发病率会降低,男性9%，女性7%。如果服用超过20年，以上疾病的整体死亡数也会降低大约4%。服用阿司匹林的好处在降低癌症死亡率方面尤为明显。

“出血的风险与许多已知因素有关，而人们需要在开始定期服用阿司匹林前了解这些因素。建议在开始每日服用前先咨询医师。” 

我们还需要进一步研究，才能更加明确服用阿司匹林的最大受益人群以及面临出血副作用的高危人群。

原文标题：Estimates of benefits and harms of prophylactic use of aspirin in the general population
原文链接：http://annonc.oxfordjournals.org/content/early/2014/07/30/annonc.mdu225.full

作者：J. Cuzick1, M. A. Thorat1, C. Bosetti, P. H. Brown, J. Burn4, N. R. Cook, L. G. Ford, E. J. Jacobs, J. A. Jankowski, C. La Vecchia, M. Law, F. Meyskens, P. M. Rothwell, H. J. Senn, A. Umar

Abstract

Background Accumulating evidence supports an effect of aspirin in reducing overall cancer incidence and mortality in the general population. We reviewed current data and assessed the benefits and harms of prophylactic use of aspirin in the general population.

Methods The effect of aspirin for site-specific cancer incidence and mortality, cardiovascular events was collated from the most recent systematic reviews. Studies identified through systematic Medline search provided data regarding harmful effects of aspirin and baseline rates of harms like gastrointestinal bleeding and peptic ulcer.

Results The effects of aspirin on cancer are not apparent until at least 3 years after the start of use, and some benefits are sustained for several years after cessation in long-term users. No differences between low and standard doses of aspirin are observed, but there were no direct comparisons. Higher doses do not appear to confer additional benefit but increase toxicities. Excess bleeding is the most important harm associated with aspirin use, and its risk and fatality rate increases with age. For average-risk individuals aged 50–65 years taking aspirin for 10 years, there would be a relative reduction of between 7% (women) and 9% (men) in the number of cancer, myocardial infarction or stroke events over a 15-year period and an overall 4% relative reduction in all deaths over a 20-year period.

Conclusions Prophylactic aspirin use for a minimum of 5 years at doses between 75 and 325 mg/day appears to have favourable benefit–harm profile; longer use is likely to have greater benefits. Further research is needed to determine the optimum dose and duration of use, to identify individuals at increased risk of bleeding, and to test effectiveness of Helicobacter pylori screening–eradication before starting aspirin prophylaxis.