 Comparison of olaparib vs. physicians choice of single agent standard of care non-platinum based chemotherapy in patients with germline Breast Cancer susceptibility gene gBRCA mutated ovarian cancer who have progressed at least 6 months after the last platinum based chemotherapy. Patient should have received at least 2 prior lines of platinum based chemotherapy. The aim of the study is to assess the efficacy and safety of olaparib tablets. 