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

Abstract

<h4>Objective</h4>To examine if endometriosis affected outcomes of ovarian clear cell carcinoma (OCCC).<h4>Methodology</h4>We searched for all study types on the databases of EMBASE, PubMed, Web of Science and Scopus. The search limits were 1^st January 2001 to 2^nd April 2025. Data on overall survival (OS) and disease-free survival (DFS) was pooled in a random-effect meta-analysis model.<h4>Results</h4>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.<h4>Conclusions</h4>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.<b>Registration No:</b> PROSPERO: CRD420251021982.