Prognostic factors of synchronous endometrial and ovarian cancers: a systematic review and meta-analysis of cohort studies

BACKGROUND: Accurate identification of prognostic factors at the time of diagnosis in patients with synchronous endometrial and ovarian cancers (SEOC) is critical for guiding aggressive treatment strategies and intensive post-treatment surveillance. However, existing studies have reported inconsistent findings regarding the direction and magnitude of these prognostic associations, likely due to limited sample sizes. This systematic review and meta-analysis aimed to comprehensively evaluate prognostic factors in SEOC patients. METHODS: Four major databases (Medline/PubMed, Embase, Scopus, and Web of Science) were systematically searched independently by two reviewers up to April 30, 2026, without time restrictions. Studies investigating prognostic factors associated with overall survival (OS) or disease-free survival (DFS) in SEOC patients were included. Heterogeneity was assessed using Cochrane's Q and I² statistics. RESULTS: Thirteen studies encompassing 26,543 patients, of whom 1,275 had SEOC. Pooled estimates revealed that lymphovascular space invasion (LVSI), myometrial invasion (MI), histologic grade, tumor stage, and endometrioid histology were significantly associated with both OS and DFS. In contrast, patient age and CA-125 levels showed no significant association with either OS or DFS. CONCLUSION: This meta-analysis, based on moderate-certainty evidence, demonstrates that LVSI, MI > 50%, tumor stage > 2, and histologic grade > 2 are associated with poorer OS and DFS in SEOC patients. Conversely, endometrioid histology confers significantly improved survival outcomes compared to non-endometrioid types. Timely and accurate assessment of these factors at diagnosis is essential for optimizing treatment intensity and post-treatment follow-up.