Distinct endometriosis involvement confers divergent oncologic outcomes in ovarian clear cell carcinoma.

Objective: To evaluate the clinicopathologic characteristics and survival outcomes of ovarian clear cell carcinoma (OCCC) patients with different endometriosis statuses.

Methods: This retrospective study included OCCC patients diagnosed between 2012 and 2021, classified into three groups based on the Sampson and Scott criteria: Without (no endometriosis), Arising (OCCC arising from endometriosis), and Coexisting (OCCC coexisting with endometriosis). Clinical and pathological characteristics were compared across groups, and survival outcomes were analyzed using Kaplan-Meier methods. Prognostic factors for progression-free survival (PFS) and overall survival (OS) were identified through univariate and multivariate analyses.

Results: Among 242 patients, 53.7% were in the Without group, 29.3% in the Arising group, and 16.9% in the Coexisting group. The Arising group had the highest prevalence of early FIGO stage disease (91.6%) compared to the Coexisting (75.6%, p = 0.041) and Without (67.7%, p = 0.000) groups. Lymph-node metastasis was significantly lower in the Arising group (2.8%) than in the Coexisting (19.5%, p = 0.010) and Without (10%, p = 0.011) groups. Notably, the Arising group demonstrated unique atypical endometriosis features. In univariate analysis, the presence of endometriosis (either arising from or coexisting with endometriosis) was associated with improved PFS (p = 0.004 and p = 0.009, respectively); however, multivariate analysis confirms only coexisting with endometriosis as an independent factor (HR: 0.11, 95% CI: 0.01-0.84). For OS, the Arising group demonstrated the most significant benefit, with a 5-year OS of 92.4% compared to the Coexisting group (83.9%, p = 0.293) and the Without group (62.6%, p = 0.023). Multivariate analysis identified only FIGO stage (HR: 5.89, 95% CI: 2.06-16.82) as an independent prognostic factor for OS, while endometriosis did not reach statistical significance (HR: 0.62, 95% CI: 0.26-1.53).

Conclusions: Classifying OCCC with endometriosis statuses reveals distinct prognostic patterns. Coexisting with endometriosis positively impacts PFS, while the Arising subgroup shows the most significant OS benefit but may be confounded with other factors.