Prevalence of endometriosis in epithelial ovarian cancer. Analysis of the associated clinical features and study on molecular mechanisms involved in the possible causality.

PURPOSE OF INVESTIGATION: To determine the prevalence of endometriosis in patients with epithelial ovarian cancer and explore the differences between women with endometrioid and clear-cell histologic subtypes with and without associated endometriosis.
MATERIALS AND METHODS: The medical charts of 496 patients with epithelial ovarian cancer at the Hospital Virgin de la Arrixaca (Murcia, Spain) between 1971 and 2010 were reviewed.
RESULTS: Endometriosis was present in 27 (5.4%) of the 496 cases (p < 0001), and was associated with the endometrioid histotype in 13/45 cases (29%) and with the clear cell histotype in 7/22 (32%). The prevalence of an association with endometriosis according to histologic type was 28.8% (13/45) for endometrioid carcinoma and 31.8% (7/22) for clear-cell carcinoma.
CONCLUSION: Both endometrioid and clear-cell ovarians tumours are associated with pelvic endometriosis. Patients with endometiosis associated ovarian cancer differ from non-endometiosis associated ovarian cancer in their clinical characteristics.