Dataset Information

Aspirin for the chemoprevention of colorectal adenomas: meta-analysis of the randomized trials.

ABSTRACT:

Background

Multiple 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.

Methods

We 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.

Results

We 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.

Conclusion

Aspirin is effective for the prevention of colorectal adenomas in individuals with a history of these lesions.

SUBMITTER: Cole BF

PROVIDER: S-EPMC5975663 | biostudies-literature | 2009 Feb

REPOSITORIES: biostudies-literature

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Publications

Aspirin for the chemoprevention of colorectal adenomas: meta-analysis of the randomized trials.

Cole Bernard F BF Logan Richard F RF Halabi Susan S Benamouzig Robert R Sandler Robert S RS Grainge Matthew J MJ Chaussade Stanislas S Baron John A JA

Journal of the National Cancer Institute 20090210 4

<h4>Background</h4>Multiple 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.<h4>Methods</h4>We combined data from all randomized double-blind placebo-controlled trials that evaluated aspirin for the preve ...[more]

PMID: 19211452

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Project description:BackgroundProtective effects of calcium supplementation against colorectal adenomas have been documented in systematic reviews; however, the results have not been conclusive. Our objective was to update and systematically evaluate the evidence for calcium supplementation taking into consideration the risks of systematic and random error and to GRADE the evidence.MethodsThe study comprised a systematic review with meta-analysis and trial sequential analysis (TSA) of randomized controlled trials (RCTs). We searched for RCTs published up until September 2016. Retrieved trials were evaluated using risk of bias. Primary outcome measures were the incidences of any recurrent adenomas and of advanced adenomas. Meta-analytic estimates were calculated with the random-effects model and random errors were evaluated with trial sequential analyses (TSAs).ResultsFive randomized trials (2234 patients with a history of adenomas) were included. Two of the 5 trials showed either unclear or high risks of bias in most criteria. Meta-analysis of good quality RCTs suggest a moderate protective effect of calcium supplementation on recurrence of adenomas (relative risk [RR], 0.88 [95% CI 0.79-0.99]); however, its effects on advanced adenomas did not show statistical significance (RR, 1.02 [95% CI 0.67-1.55]). Subgroup analyses demonstrated a greater protective effect on recurrence of adenomas with elemental calcium dose ?1600?mg/day (RR, 0.74 [95% CI 0.56-0.97]) compared to ?1200?mg/day (RR, 0.84 [95% CI 0.73-0.97]). No major serious adverse events were associated with the use of calcium, but there was an increase in the incidence of hypercalcemia (P?=?.0095). TSA indicated a lack of firm evidence for a beneficial effect. Concerns with directness and imprecision rated down the quality of the evidence to "low."ConclusionThe available good quality RCTs suggests a possible beneficial effect of calcium supplementation on the recurrence of adenomas; however, TSA indicated that the accumulated evidence is still inconclusive. Using GRADE-methodology, we conclude that the quality of evidence is low. Large well-designed randomized trials with low risk of bias are needed.

Dataset Information

Aspirin for the chemoprevention of colorectal adenomas: meta-analysis of the randomized trials.

Background

Methods

Results

Conclusion

Publications

Aspirin for the chemoprevention of colorectal adenomas: meta-analysis of the randomized trials.

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