The origin of endometriosis-associated ovarian cancer from uterine neoplastic lesions.

Endometriosis is a risk factor for type I epithelial ovarian cancer but an issue to be clarified is the site of origin of endometriosis associated ovarian cancer. Here we proposed that the uterus may be the organ of origin of ovarian endometrioid cancer associated with endometriosis. Thus, the first neoplastic transformation would characterize the uterine cells migrating in the pelvis via retrograde menstruation and they would implant secondarily on the ovary. Supporting this hypothesis, an higher incidence of synchronous precancerous and cancerous endometrial pathology in patients affected by ovarian endometrioid cancer associated with endometriosis was showed. Moreover, uterine endometrial type I carcinoma resembles endometriosis associated endometrioid ovarian cancer in behavior and prognosis. This hypothesis is also supported by epidemiologic evidence showing a protective effect for tubal ligation and oral contraceptive use for endometriosis associated endometrioid ovarian cancer. Endometriosis and endometrioid ovarian carcinoma might represent two distinct biological entities characterized by the same organ of origin (the uterus), the same pathogenetic mechanism (transtubal reflux) and the same target organ (the ovary). By shifting the early events of ovarian carcinogenesis to the endometrium, prevention approaches as salpingectomy/tubal ligation and intervention at uterine corpus level may play an important role.