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

OBJECTIVE

Since 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.

METHODS

This 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.

RESULTS

Out 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 >1cm, 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).

CONCLUSIONS

Our 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.