Operability and chemotherapy responsiveness in advanced low-grade serous ovarian cancer. An analysis of the AGO Study Group metadatabase

• Primary low-grade serous ovarian cancer (LGSOC) is not as responsive to platinum-taxane-based chemotherapy as high-grade serous advanced ovarian cancer (HGSOC)
• Surgical debulking showed a similar impact on outcome in primary LGSOC and HGSOC however LGSOC were associated with better prognosis
• LGSOC is less responsive to platinum-taxane-based chemotherapy Surgical debulking showed a similar impact on outcome in LGSOC and HGSOC

ObjectiveSince almost two decades standard 1st-line chemotherapy for advanced ovarian cancer (AOC) has been a platinum/taxane combination. More recently, this general strategy has been challenged because different types of AOC may not benefit homogenously. Low-grade serous ovarian cancer (LGSOC) is one of the candidates in whom efficacy of standard chemotherapy should be revised.MethodsThis study is an exploratory case control study of the AGO-metadatabase of 4 randomized phase III trials with first-line platinum combination chemotherapy without any targeted therapy. Patients with advanced FIGO IIIBIV low-grade serous ovarian cancer were included and compared with control cases having high-grade serous AOC.ResultsOut of 5114 patients in this AGO database 145 (2.8%) had LGSOC and of those thirty-nine (24.1%) had suboptimal debulking with post-operative residual tumor > 1 cm, thus being eligible for response evaluation. An objective response was observed in only 10 patients and this 23.1% response rate (RR) was significantly lower compared to 90.1% RR in the control cohort of high-grade serous ovarian cancer (HGSOC) (p < 0.001). Both, LGSOC and HGSOC patients who underwent complete cytoreduction had significantly better progression free survival (PFS) and overall survival (OS) in comparison to those with residuals after primary surgery, accordingly (p < 0.001).ConclusionsOur observation indicates that low-grade serous cancer is not as responsive to platinum-taxane-based chemotherapy as high-grade serous AOC. In contrast, surgical debulking showed a similar impact on outcome in both types of AOC thus indicating different roles for both standard treatment modalities. Systemic treatment of low grade serous AOC urgently warrants further investigations.