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Aspirin in the chemoprevention of colorectal neoplasia: an overview.

ABSTRACT: Considerable evidence supports the effectiveness of aspirin for chemoprevention of colorectal cancer (CRC) in addition to its well-established benefits in the prevention of vascular disease. Epidemiologic studies have consistently observed an inverse association between aspirin use and risk of CRC. A recent pooled analysis of a long-term posttrial follow-up of nearly 14,000 patients from four randomized, cardiovascular disease prevention trials showed that daily aspirin treatment for about five years was associated with a 34% reduction in 20-year CRC mortality. A separate metaanalysis of nearly 3,000 patients with a history of colorectal adenoma or cancer in four randomized adenoma prevention trials showed that aspirin reduced the occurrence of advanced adenomas by 28% and any adenoma by 17%. Aspirin has also been shown to be beneficial in a clinical trial of patients with Lynch syndrome, a hereditary CRC syndrome; in those treated with aspirin for at least two years, there was a 50% or more reduction in the risk of CRC commencing five years after randomization and after aspirin had been discontinued. A few observational studies have shown an increase in survival among patients with CRC who use aspirin. Taken together, these findings strengthen the case for consideration of long-term aspirin use in CRC prevention. Despite these compelling data, there is a lack of consensus about the balance of risks and benefits associated with long-term aspirin use, particularly in low-risk populations. The optimal dose to use for cancer prevention and the precise mechanism underlying aspirin's anticancer effect require further investigation.

SUBMITTER: Chan AT

PROVIDER: S-EPMC3273592 | biostudies-literature | 2012 Feb

REPOSITORIES: biostudies-literature

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Aspirin in the chemoprevention of colorectal neoplasia: an overview.

Chan Andrew T AT Arber Nadir N Burn John J Chia Whay Kuang WK Elwood Peter P Hull Mark A MA Logan Richard F RF Rothwell Peter M PM Schrör Karsten K Baron John A JA

Cancer prevention research (Philadelphia, Pa.) 20111114 2

Considerable evidence supports the effectiveness of aspirin for chemoprevention of colorectal cancer (CRC) in addition to its well-established benefits in the prevention of vascular disease. Epidemiologic studies have consistently observed an inverse association between aspirin use and risk of CRC. A recent pooled analysis of a long-term posttrial follow-up of nearly 14,000 patients from four randomized, cardiovascular disease prevention trials showed that daily aspirin treatment for about five ...[more]

PMID: 22084361

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Project description:Objective To assess the comparative efficacy and safety of candidate agents (low and high dose aspirin, non-aspirin non-steroidal anti-inflammatory drugs (NSAIDs), calcium, vitamin D, folic acid, alone or in combination) for prevention of advanced metachronous neoplasia (that is, occurring at different times after resection of initial neoplasia) in individuals with previous colorectal neoplasia, through a systematic review and network meta-analysis.Data sources Medline, Embase, Web of Science, from inception to 15 October 2015; clinical trial registries.Study selection Randomized controlled trials in adults with previous colorectal neoplasia, treated with candidate chemoprevention agents, and compared with placebo or another candidate agent. Primary efficacy outcome was risk of advanced metachronous neoplasia; safety outcome was serious adverse events.Data extraction Two investigators identified studies and abstracted data. A Bayesian network meta-analysis was performed and relative ranking of agents was assessed with surface under the cumulative ranking (SUCRA) probabilities (ranging from 1, indicating that the treatment has a high likelihood to be best, to 0, indicating the treatment has a high likelihood to be worst). Quality of evidence was appraised with GRADE criteria.Results 15 randomized controlled trials (12 234 patients) comparing 10 different strategies were included. Compared with placebo, non-aspirin NSAIDs were ranked best for preventing advanced metachronous neoplasia (odds ratio 0.37, 95% credible interval 0.24 to 0.53; SUCRA=0.98; high quality evidence), followed by low-dose aspirin (0.71, 0.41 to 1.23; SUCRA=0.67; low quality evidence). Low dose aspirin, however, was ranked the safest among chemoprevention agents (0.78, 0.43 to 1.38; SUCRA=0.84), whereas non-aspirin NSAIDs (1.23, 0.95 to 1.64; SUCRA=0.26) were ranked low for safety. High dose aspirin was comparable with low dose aspirin in efficacy (1.12, 0.59 to 2.10; SUCRA=0.58) but had an inferior safety profile (SUCRA=0.51). Efficacy of agents for reducing metachronous colorectal cancer could not be estimated.Conclusions Among individuals with previous colorectal neoplasia, non-aspirin NSAIDs are the most effective agents for the prevention of advanced metachronous neoplasia, whereas low dose aspirin has the most favorable risk:benefit profile.Registration PROSPERO (CRD42015029598).

Project description:BackgroundMultiple lines of evidence indicate that aspirin has an antineoplastic effect in the large bowel. Randomized clinical trials have been conducted to evaluate the effectiveness of aspirin for reducing the risk of colorectal adenomas. A meta-analysis of these trials will provide more precise estimates of the aspirin effect, both overall and in subgroups.MethodsWe combined data from all randomized double-blind placebo-controlled trials that evaluated aspirin for the prevention of colorectal adenomas. We used random-effects meta-analysis to estimate risk ratios and 95% confidence intervals (CIs) for the effect of aspirin on the occurrence of adenomas and of advanced lesions (ie, tubulovillous adenomas, villous adenomas, adenomas >or=1 cm in diameter, adenomas with high-grade dysplasia, or invasive cancer). All statistical tests were two-sided.ResultsWe identified four clinical trials with 2967 randomly assigned participants. Each trial evaluated aspirin for the secondary prevention of colorectal adenomas. Doses of aspirin tested ranged from 81 to 325 mg/d. The average age of participants at baseline was 58 years, and 60% were male. Median follow-up was 33 months. A total of 2698 participants underwent colonoscopic follow-up and were included in the analysis of adenoma occurrence and advanced-lesion occurrence after randomization. Among these participants, adenomas were found in 424 (37%) of the 1156 participants allocated to placebo and in 507 (33%) of the 1542 participants allocated to any dose of aspirin. Advanced lesions were found in 12% of participants in the placebo group and in 9% of participants allocated to any dose of aspirin. The pooled risk ratio of any adenoma for any dose of aspirin vs placebo was 0.83 (95% CI = 0.72 to 0.96). This corresponded to an absolute risk reduction of 6.7% (95% CI = 3.2% to 10.2%). For any advanced lesion, the pooled risk ratio was 0.72 (95% CI = 0.57 to 0.90). We found no statistically significant effect modification for any of the baseline factors studied.ConclusionAspirin is effective for the prevention of colorectal adenomas in individuals with a history of these lesions.

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Aspirin in the chemoprevention of colorectal neoplasia: an overview.

Publications

Aspirin in the chemoprevention of colorectal neoplasia: an overview.

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