881P - Response to chemotherapy in relapsed low-grade serous ovarian carcinoma: Royal Marsden series of 46 patients

Abstract

Low-grade serous carcinoma (LGSC) of the ovary/peritoneum is characterised by relative resistance to chemotherapy, however there are no reported prospective studies of chemotherapy specifically in this rare subtype. The purpose of this study was to evaluate the response to chemotherapy in patients with relapsed LGSC treated at a single cancer centre. A search of a database of patients with histologically confirmed LGSC treated at the Royal Marsden Hospital between 1990-2015 was performed. Patients treated with chemotherapy in the relapsed setting with radiologically evaluable disease were included in the study. Histological confirmation of LGSC was performed by a gynae-oncology pathologist. Response was determined by Response Evaluation Criteria in Solid Tumours (RECIST) 1.1 and confirmed by a radiologist. The primary endpoint was objective response rate (ORR). Secondary endpoints included overall survival (OS) and progression-free survival (PFS). Forty-six patients with relapsed LGSC with evaluable disease, treated with 77 separate chemotherapy regimens were included in the study. The median age at diagnosis was 49 years (range 22-80 years). There were 8 partial responses with an ORR of 10.4%. The median duration of response was 11.2 months. Stable disease was achieved in 58 of 77 (75.3%) treatment regimens. The stable disease rate at 6 months was 43%. The ORR for the platinum-sensitive cohort was 11.3% and 8.3% for the platinum-resistant cohort. The median OS was 62 months and median PFS was 8.2 months. Relapsed LGSC is relatively resistant to chemotherapy in comparison to the most common subtype, high-grade serous carcinoma. In our series, the response rate to chemotherapy (10.4%) for recurrent LGSC is higher than previously published retrospective series (3.7%). Chemotherapy should be considered an option for recurrent LGSC. There is an urgent need for better therapies and identification of LGSC patients who are more likely to respond to chemotherapy. Patients should be enrolled into clinical trials of novel targeted agents.