Clear cell ovarian cancer and endometriosis: is there a relationship?

INTRODUCTION: Ovarian clear cell carcinoma is a rare type of ovarian cancer. In recent years, issues of the common genetic origin of endometriosis and ovarian clear cell carcinoma have been raised. AIM OF THIS STUDY: Aim of this study was to evaluate the prevalence of this type of cancer, risk factors, prognosis and its potential aetiological association with endometriosis. MATERIAL AND METHODS: In a retrospective study, we analysed histopathological data of patients operated in the First Department of Gynaecology and Obstetrics (MU, Lodz) due to ovarian cancer in 2004-2014. Among the 394 patients operated on for ovarian cancer, clear cell carcinoma was found in 0.02% (9/394). Menstrual history, parity, comorbidities, data from physical examination, operational protocols and histopathological diagnoses were analysed. Follow-up was obtained from 77.8% of patients. Statistical analysis was performed using Microsoft Excel 2013. RESULTS: The mean age of patients at diagnosis was 57.6 years; the BMI in the study group was 27.2; the majority of patients were multiparous (77.8%). Clear cell carcinoma was detected mostly at stage Ia (n = 4). The concentration of Ca125 in the study group had an average of 142.75 U/ml and a median of 69.3 U/ml. The coexistence of endometriosis could not be clinically or histologically confirmed amongst our patients. The most common comorbidity in the study group was hypertension. CONCLUSIONS: In our clinical material, ovarian clear cell carcinoma is a rare histopathological specimen with a prognostic value comparable to that of serous ovarian cancer. Due to the rarity of this histopathological subtype, proving a cause-and-effect relationship between it and endometriosis can only be elucidated through statistical studies of the entire population.