Comparing the Histopathologic Patterns and Survival Outcomes of Mucinous vs Non-mucinous Colorectal Adenocarcinoma: A Systematic Review and Meta-Analysis.

Several studies have been conducted to explore the histopathological features and survival outcomes between colorectal mucinous adenocarcinoma (MAC) and adenocarcinoma (AC), with divergent outcomes being realized. Therefore, the objective of this study is to systematically compare mucinous and non-mucinous colorectal AC based on histopathologic features and survival outcomes (overall survival (OS) and disease-free survival (DFS)) and determine whether the mucinous subtype confers a distinct prognostic disadvantage. To attain this objective, we conducted a systematic review and meta-analysis by searching various online databases, including PubMed, Embase, Scopus, Web of Science, and Cochrane for studies published between 2015 and November 2025. The quality of the included studies was evaluated using the Newcastle-Ottawa Scale (NOS), and all the studies were rated as moderate to high quality. This was followed by the calculation of pooled odds ratios (ORs) and hazard ratios (HRs), as well as the corresponding 95% confidence intervals (CIs) using random-effects models to evaluate the histopathological patterns and survival outcomes between MAC and AC. A total of 12 studies involving 346,372 patients satisfied the study inclusion criteria, leading to their inclusion in this systematic review and meta-analysis. The meta-analysis disclosed that MAC was linked to a statistically significant 44% increment in mortality risk in comparison to non-MAC patients (pooled HR = 1.44, 95% CI: 1.06-1.96, p = 0.020). Further, the subgroup analyses disclosed that the adverse prognostic effect of MAC was increasingly pronounced in colon cancer (HR = 1.65), as well as in the advanced-stage (stage IV) disease (HR = 1.89). No significant bias was disclosed by the assessment of publication bias using the funnel plot symmetry and Egger's test. In conclusion, the meta-analysis has confirmed that MAC is a significant negative prognostic factor in colorectal cancers and is linked to poor OS. Though the adverse effects are consistent across different populations, they are predominantly strong in colon cancer and advanced-stage disease patients.