AbstractBackground and Aim:
We conducted a systematic review and meta-analysis to identify personal, lifestyle, and tumor-related risk factors for metachronous colorectal cancer (CRC) and polyp.Methods:
Relevant studies were identified by searching MEDLINE, Web of Science and Cochrane Central Register through 15 May 2016. Estimates for associations were summarized using random effects models.Results:
Fifty-five studies were included in the review. For individuals who had a CRC resection, having a synchronous polyp was a risk factor for metachronous CRC or polyp (relative risk [RR], 2.04; 95% confidence interval [CI], 1.48–2.82) and having a synchronous CRC (RR, 1.90; 95% CI, 1.25–2.91) and proximally located CRC (RR, 2.12; 95% CI, 1.24–3.64) were risk factors for metachronous CRC. For individuals who had a polypectomy, larger size (RR, 4.26; 95% CI, 2.11–8.57) or severe dysplasia of the initial polyp (RR, 5.15; 95% CI, 2.02–13.14), and having a synchronous polyp (RR, 2.52; 95% CI, 1.35–4.73) were risk factors for metachronous CRC; and a family history of CRC (RR, 1.90; 95% CI, 1.26–2.87), having a synchronous polyp (RR, 2.47; 95% CI, 1.74–3.50) and a larger size (RR, 1.49; 95% CI, 1.03–2.15) and proximal location of the initial polyp (RR, 1.20; 95% CI, 1.02–1.40) were risk factors for metachronous polyp. Meta-regression showed duration of follow-up was not a source of heterogeneity for most associations. There was no evidence that lifestyle factors were associated with metachronous CRC or polyp risk.Conclusion:
A comprehensive list of risk factors identified for metachronous CRC or polyp may have important clinical implications.