Prospective, monocentric study aiming to identify factors involved in platinum based-chemotherapy resistance in patients with epithelial ovarian cancer (all stages). Patients will receive treatment (platinum based-chemotherapy) according to the standard practices. A prospective database and an associated biological collection will be performed during 5 years: * For each patient: clinical, biological, epidemiological and therapeutic treatment data will be collected during the standard therapeutic care. * Biological samples (blood samples, tumor biopsy specimens and ascites samples) will be collected for all patients. These samples will be collected at the same time as those taken in standard practice (no additional biopsy will be performed for the study). Study participation of each patient will be 5 years.