Impact of endometriosis on survival outcomes in ovarian cancer patients: a pilot study

The aim of our study is to investigate the percentage of ovarian cancer (OC) patients with concomitant endometriosis and its distribution across histological subtypes, and to assess whether the presence of endometriosis influences overall survival (OS) and disease-free survival (DFS) in patients with clear cell and endometrioid OC.

We conducted a retrospective observational study using patient's medical records of two reference hospitals in Spain, including OC patients, with and without endometriosis. We analysed the frequency of the association between cancer and endometriosis, the differences in OS and DFS survival between patients with and without endometriosis and the influence of age, tumour size, histological subtype and grade.

Among the 257 patients included, 39 (15.2%) had concomitant endometriosis. This correlation was particularly strong in endometrioid (EC) and clear cell carcinoma (CCC) patients; 61.0% of whom have concomitant endometriosis. Survival analysis demonstrated that, in EC and clear CCC, endometriosis-associated patients had longer OS (HR = 0.1773 [IC95% 0.03053-1.019]) and DFS (HR = 0.02 [IC95% 0.0009266-0.5100]) than OC patients without endometriosis. The difference was statistically significant for OS (p = 0.0174) but not for DFS (p = 0.0525). Univariate analysis shows that age, BMI or cyst size did not significantly affect disease outcomes.

Endometriosis has a clear association with EC and CCC. Its presence improves OS in Ovarian Cancer patients. Further studies are needed to confirm the improvement in outcomes and to determine the nature of the putative protection.