High-grade serous ovarian cancer remains highly lethal, with most patients experiencing recurrence and poor prognosis due to late diagnosis and limited screening. Standard treatment combines surgery with chemotherapy, and neoadjuvant chemotherapy for advanced cases. This project aimed to improve survival outcomes by demonstrating the benefits of centralized surgery in Belgium and the positive effect of per operative administration of ketorolac on survival. A prospective study then assessed tumor genetic instability pre- and post-neoadjuvant chemotherapy using whole genome and exome sequencing. We do not find any genetic differences correlated with treatment response, but we observed that patients with poor prognosis exhibited more DNA repair defects scars, particularly loss of heterozygosity. This work establishes a foundation for analyzing genetic shifts in high-grade serous ovarian cancer during chemotherapy