Inclusion Criteria:  Patients are eligible to be included in the study only if they met all the following criteria:  Female Patients must be ≥18 years old at diagnosis. Patients with newly diagnosed, histologically confirmed, advanced (FIGO stage III-IV) ovarian cancer, primary peritoneal cancer and / or fallopian-tube cancer and received olaparib from Aug 2018 up to Dec 2020 (the time range could be extended in order to recruit enough eligible subjects as required). Patients must have a tumor BRCA testing result which is tBRCAwt, defined as tumor BRCA wild type (patients without evidence of BRCA 1 and/or BRCA 2 deleterious or suspected deleterious mutations). Patients who have completed first-line platinum-based chemotherapy and were in clinical complete response (CR) or in partial response (PR). Patients who were still in CR or PR before receiving maintenance therapy. Patients who received at least one dose of olaparib tablets monotherapy as maintenance therapy within three months after platinum-based chemotherapy and without disease progression.  Exclusion Criteria:  Patients are excluded if any of the following factors were present:  Patient with multiple primary cancers as reported in EMR. Concomitant any anti- cancer therapy (chemotherapy, immunotherapy, hormonal therapy (Hormone replacement therapy (HRT) is acceptable), radiotherapy, biological therapy or other novel agent) during Olaparib maintenance. Any previous treatment with PARP inhibitor. Patients with myelodysplastic syndrome/acute myeloid leukaemia or with features suggestive of MDS/AML. Patients with symptomatic uncontrolled brain metastases. Any other concerns related to decreased efficacy and safety of maintenance therapy.