Clinicopathological and prognostic features of colorectal mucinous adenocarcinomas: a systematic review and meta-analysis.

Background: Many studies have explored the clinicopathological features and prognosis between colorectal mucinous adenocarcinoma (MAC) and adenocarcinoma (AC) and have given different results. This meta-analysis summarizes previous evidence and evaluates the clinicopathological and prognostic features of MAC relative to AC in colorectal cancers (CRCs).

Methods: The meta-analysis was conducted by searching the databases of PubMed, China National Knowledge Infrastructure (CNKI), WANFANG data, Embase, and Web of Science. Pooled odds ratios (ORs) and hazard ratios (HRs) and corresponding 95% confidence intervals (CIs) were calculated to assess the clinicopathological and prognostic differences between MAC and AC.

Results: Fifty-six studies involving 803157 patients met the inclusion criteria and were included in this meta-analysis. The clinicopathological features of MAC were greatly different from AC, except for lymphatic invasion (OR = 1.07, 95% CI: 0.99-1.15, P = 0.09) and perineural invasion (OR = 0.92, 95% CI: 0.79-1.06, P = 0.09). Further investigation found that MAC predicted poor OS (HR = 1.04, 95% CI: 1.03-1.04, P < 0.01), but not DFS in CRCs (HR = 1.01,95% CI: 0.88- 1.17, P = 0.85). Subgroup analysis found that MAC was obviously correlated with OS in patients with different recruitment time, with tumor located in rectum, from different regions, with different sample sizes and with TNM stage in II, and calculated by different data types(P < 0.01).

Conclusions: This study shows that MAC displays obviously different clinicopathological features compared with AC. And MAC has a poor OS relative to AC but the DFS was comparable.