Patterns of Recurrence and Role of Pelvic Radiotherapy in Ovarian Clear Cell Adenocarcinoma

Objective(s): The aims of this study were to analyze patterns of recurrence in patients with ovarian clear cell adenocarcinoma (CCA) and to evaluate the role of pelvic radiotherapy (RT). Methods and Materials: All patients with ovarian CCA treated at a single institution between 1989 and 2012 were identified, and their medical records were reviewed. Eligibility criteria included histologic diagnosis of pure CCA of the ovary, surgical staging for International Federation of Gynecology and Obstetrics stage I-to-IIIC disease, and adjuvant or neoadjuvant chemotherapy. Selected end pointswere 3-, 5-, and 8-year cumulative incidence of pelvic recurrence (CIPR). Results: Fifty-six patients met eligibility criteria. Most received intravenous carboplatin and paclitaxel for a median of 6 cycles. Six patients (10.7%) received pelvic RT, and 50 (89.3%) did not. Pelvic RT patients had stage I-to-IIC disease. Median follow-up was 39 months (range, 1Y69 months). For the group as a whole, 14 patients (25%) had initial disease recurrence involving the pelvis, whereas 6 (10.7%) had first recurrence outside the pelvis. Three-, 5- and 8-year CIPR were 28.2%, 38.5%, and 43.2%, respectively. There was no significant difference in 3-, 5-, or 8-year CIPR between the group of patients receiving RT (20%, 20%, and 20%) and a group of patients with stages I to IIC who did not receive RT (9.9%, 22.4%, and 30.2%), P = 0.22. During RT, patients developed mild grade 1-to-2 side effects. After RT, 1 patient developed lower extremity lymphedema with recurrent cellulitis. One patient who developed small bowel obstruction before RT developed small bowel radiation enteritis and obstruction after RT, ultimately requiring surgical intervention. Conclusions: These findings suggest that ovarian CCA exhibits a propensity for pelvic recurrence after surgery and chemotherapy. RT, a local treatment that can effectively sterilize microscopic tumor cells, may benefit patients with this disease. Prospective studies with sufficient statistical power are warranted to further evaluate the role of RT.