The association between endometriosis and gynecological cancers and breast cancer: A review of epidemiological data

Objective. This article critically reviews the literature on the association between endometriosis and gynecological cancers and breast cancer, based on epidemiologic data. Methods. Literature review of the English language literature based on searching in the MEDLINE (PubMed) database and additional collection of reports by systematically reviewing all references from retrieved papers. Results. Data from large cohort and case-control studies indicate that endometriosis patients only have an increased risk of ovarian cancer among the gynecological malignancies and breast cancer, although most of the observed associations are modest. Data on the association between endometriosis and breast cancer are inconsistent. Endometriosis patients have a reduced risk of cervical cancer, and there is no association between endometriosis and endometrial cancer. Endometriosis-associated ovarian cancer seems to be a distinct clinical entity; patients are younger, diagnosed in earlier stages, have lower grade lesions and a better survival. Further, endometriosis-associated ovarian cancers are predominantly clear cell and endometrioid histologic subtypes. Conclusions. Endometriosis seems to be a precursor of epithelial ovarian cancer, especially clear cell and endometrioid adenocarcinomas. However, current evidence is insufficient to draw any definitive conclusions whether this association represents causality or the sharing of similar risk factors and/or antecedent mechanisms. (C) 2011 Elsevier Inc. All rights reserved.