Purpose: Although endometriosis is a benign disorder, recent studies suggest that endometriosis could be viewed as a neoplastic process. The objective of this study is to explore the epidemiology of synchronous neoplasms (SPN) in women with severe endometriosis.

Patients and Methods: The prevalence of SPN in cases with endometriotic ovarian cysts that underwent surgery at ‘Lito’ Maternity Hospital of Athens and at Anticancer Institute of Bucharest was investigated. The review period was from the year 2000 to 2008. The medical records and pathology were reviewed to confirm the diagnosis and stage of tumors.

Results: Five women with synchronous cancer of the genital tract were identified. All of our patients had a grade–Ⅰ endometrioid carcinoma of the uterus (Ⅰa in 3, Ⅱb in 2). Myometrium was invaded in less than 1/3, in 4 cases, and less than ½ in one case. Similarly, 4 out of 5 ovarian cancers were endometrioid, while one was serum cystadenosarcoma. All of the ovarian malignancies were grade Ⅰ (Ⅰb in 3 and Ⅰa in 2). The median diameter of the ovarian neoplasias was of 4.3cm, as opposed to 4.5cm that was the median diameter of all endometrioid cysts. When the larger ovarian malignant cyst in each patient was accounted, the median diameter was calculated as having 5.8cm.

Conclusions: Women with synchronous primary cancers of the endometrium and ovary have distinct clinical characteristics including younger age, premenopausal status, and nulliparity. This suggests that a hormonal ‘field effect’ may account for the development of these simultaneous endometrioid cancers, supporting the theory of estrogen receptors.