RecruitingDrug trialNiraparib Maintenance Treatment in Patients With Newly Diagnosed Advanced Platinum- Sensitive, OC. The First Poland RWE Study.The study is observational, not interventional. The study will include patients with advanced ovarian cancer who have been treated in Poland based on a previous early access program, and who are currently being treated under the B.50 drug program, funded by the National Health Fund. Only patients currently being treated in the B.50 program at 10 selected centers listed on this site may be included in the study. Of course, any patient in Poland eligible for maintenance treatment with niraparib can receive the drug, regardless of participation in this RWE study.The treatment involves administering niraparib as maintenance therapy for 3 years after the completion of chemotherapy, provided that the patient has responded to systemic treatment (NED, CR, PR).