Chemoprevention of colorectal cancer in general population and high-risk population: a systematic review and network meta-analysis.

BACKGROUND

Many nutritional supplements and pharmacological agents have been reported to show preventive effects on colorectal adenoma and colorectal cancer (CRC). We performed a network meta-analysis to summarize such evidence and assess the efficacy and safety of these agents.

METHODS

We searched PubMed, Embase, and the Cochrane Library for studies published in English until October 31, 2021 that fit our inclusion criteria. We performed a systematic review and network meta-analysis to assess the comparative efficacy and safety of candidate agents (low-dose aspirin [Asp], high-dose Asp, cyclooxygenase-2 inhibitors [coxibs], calcium, vitamin D, folic acid, ursodeoxycholic acid [UDCA], estrogen, and progesterone, alone or in combination) for preventing colorectal adenoma and CRC. Cochrane risk-of-bias assessment tool was employed to evaluate the quality of each included study.

RESULTS

Thirty-two randomized controlled trials (278,694 participants) comparing 13 different interventions were included. Coxibs significantly reduced the risk of colorectal adenoma (risk ratio [RR]: 0.59, 95% confidence interval [CI]: 0.44-0.79, six trials involving 5486 participants), advanced adenoma (RR: 0.63, 95% CI: 0.43-0.92, four trials involving 4723 participants), and metachronous adenoma (RR: 0.58, 95% CI: 0.43-0.79, five trials involving 5258 participants) compared with placebo. Coxibs also significantly increased the risk of severe adverse events (RR: 1.29, 95% CI: 1.13-1.47, six trials involving 7109 participants). Other interventions, including Asp, folic acid, UDCA, vitamin D, and calcium, did not reduce the risk of colorectal adenoma in the general and high-risk populations compared with placebo.

CONCLUSIONS

Considering the balance between benefits and harms, regular use of coxibs for prevention of colorectal adenoma was not supported by the current evidence. Benefit of low-dose Asp for chemoprevention of colorectal adenoma still requires further evidence.

REGISTRATION

PROSPERO, No. CRD42022296376.