Association between endometriosis and prognosis of ovarian clear cell carcinoma: A systematic review and meta-analysis

Abstract

Objective: To examine if endometriosis affected outcomes of ovarian clear cell carcinoma (OCCC).

Methodology: We searched for all study types on the databases of EMBASE, PubMed, Web of Science and Scopus. The search limits were 1st January 2001 to 2nd April 2025. Data on overall survival (OS) and disease-free survival (DFS) was pooled in a random-effect meta-analysis model.

Results: Nineteen studies were included. Pooling of the data showed that endometriosis-associated OCCC had statistically significant improved DFS (HR: 0.80 95% CI: 0.64, 0.99) as compared to non-endometriosis-associated OCCC, but there seemed to be no difference for OS (HR: 0.79 95% CI: 0.62, 1.01) between the two groups. However, the efficacy was not found to be stable on sensitivity analysis and turned significant (for OS) and non-significant (for DFS) on removal of multiple studies. Subgroup analysis based on study location, sample size (>150 or <150), cancer stage (early only or all stages), type of data (crude or adjusted) and follow-up (<5 or >5 years) showed mixed results.

Conclusions: Low-quality evidence from retrospective studies indicates that there may be a tendency of improved DFS in endometriosis-associated OCCC but there may be no difference in OS. Lack of stability of the results on sensitivity and subgroup analyses are important drawbacks that limit strong conclusions.