Olaparib Treatment in Relapsed Germline Breast Cancer Susceptibility Gene (BRCA) Mutated Ovarian Cancer Patients Who Have Progressed at Least 6 Months After Last Platinum Treatment and Have Received at Least 2 Prior Platinum Treatments

Inclusion Criteria:

* Patients must be ≥ 18 years of age
* Patients with histologically diagnosed relapsed high grade serous ovarian cancer (including primary peritoneal and/or fallopian tube cancer) or high grade endometrioid cancer. Patients are eligible to undergo BRCA testing even if they have not yet had recurrence or progression of disease \>6 months (\>/=183 days) after completion of their last platinum therapy.
* Documented germline mutation in Breast Cancer susceptibility genes: BRCA1 and/or BRCA2 that is predicted to be deleterious or suspected deleterious (known or predicted to be detrimental/lead to loss of function)
* At least one lesion that can be accurately assessed at baseline by CT/MRI and is suitable for repeated assessment.
* Patients must have received at least 2 prior platinum based lines of chemotherapy - Patients must be partially platinum sensitive or platinum sensitive
* Patients must be suitable to start treatment with single agent chemotherapy based on physician's choice
* Patients must have normal organ and bone marrow function measured within 28 days of randomisation,
* Eastern Cooperative Oncology Group (ECOG) performance status 0-2
* Patients must have a life expectancy ≥ 16 weeks
* Formalin fixed, paraffin embedded tumour sample from the primary or recurrent cancer must be available for central testing.

Exclusion Criteria:

* BRCA 1 and/or BRCA2 mutations that are considered to be non detrimental
* Exposure to any investigational product within 30 days or 5 half lives (whichever is longer) prior to randomisation
* Any previous treatment with a Polyadenosine 5'diphosphoribose polymerisation (PARP) inhibitor, including olaparib.
* Patients who have platinum resistant or refractory disease
* Patients receiving any systemic chemotherapy within 3 weeks prior to first dose of study treatment
* Previous single agent exposure to the selected chemotherapy regimen for randomisation. - Prior malignancy in the last 5 years, unless curatively treated and recurrence free (few exceptions apply).