The investigators therefore propose to conduct a biological study of prospectively collected patient tumour samples, ascites, blood and other residual samples (feces, urine, vaginal smear) throughout the disease course where markers (at diagnosis and their change with treatment) will be correlated to outcome in order to investigate how genetic diversity in OC prior to treatment and adaptation following treatment contribute to chemotherapy resistance. In addition freshly collected ascitic samples (and tumour samples) will be subjected to ex vivo DNA repair functional assays and isolated in primary culture (and established as xenografts) for target validation experiments.

Inclusion Criteria:

1. New patient with a diagnosis of OC, or
2. Previously treated patient with frozen or formalin fixed paraffin embedded primary tumour sample available that can be retrieved by the center presenting with progressive disease, and consenting to CT guided biopsy of relapsed disease, or
3. Previously treated patient with frozen or formalin fixed paraffin embedded primary tumour sample available that can be retrieved by the center scheduled for surgery for relapsed disease.
4. Signed informed consent
5. Age ≥ 18
6. Patient affiliated to a social security regimen or beneficiary of the same

Exclusion Criteria:

1. Patients who do not fit the inclusion criteria and those who refuse an antitumoral treatment;
2. Coagulation abnormalities that contra-indicates the biopsy