Association between ovarian cancer and advanced endometriosis

We retrospectively analyzed clinicopathological data in two different countries over the past years on the association between ovarian endometriosis and ovarian carcinoma. Medical and pathological reports were evaluated from 1,000 patients with endometriosis from two different geographical areas. The prevalence and women characteristics of cases were analyzed. Endometriosis-associated ovarian cancer was present in 20 (2%) cases, among the study subjects. The observed prevalence was 12 (60%) for endometrioid carcinoma, 4 (20%) for clear cell ovarian carcinoma, 2 (10%) for serous and 2 (10%) for mucinous adenocarcinoma. A higher proportion of endometrioid carcinoma cases were noted in comparison with other types (P<0.001). We found only 3/20 (15%) postmenopausal cases. In all cases, we reported advanced stage of endometriosis (stage III or IV). Left-sided endometrioid carcinoma were notably more common than right-sided ones (P<0.001). In the majority of cases, malignant transformation of endometriosis was observed in endometrioid carcinoma or clear cell carcinoma of the ovary. Further research is required to establish the relationship between endometriosis and ovarian cancer.