Introduction/Background Patients with homologous recombination deficient high grade serous ovarian cancer have increased sensitivity to platinum based chemotherapy and maintenance therapy with PARPi, leading to improved survival outcomes. The prognostic outcome of different genetic anomalies and of GIS score on survival is not well known. Tailored treatment considering different genetic anomalies would lead to more effective management of the disease.

Methodology Retrospective single institution study including patients treated for stage III-IV ovarian cancer with complete cytoreduction, and available genetic and treatment data. Data collected for this study included genetic data (type of mutation, HRD GIS score), treatment, and survival data. Data were analyzed using STATA 15.0.

Results 139 patients were included in the study. 67 patients (48.2%) had HRD, and 42 patients (30.2%) had BRCA mutation. 120 (86.3%) underwent cytoreductive surgery, 57 patients (41.0%) underwent primary debulking surgery, and 82 (59.0%) were treated with neoadjuvant chemotherapy and interval debulking surgery.

There was no difference in PFS according to the type of genetic anomaly or the GIS score, with a 2-year PFS of 56.2% [42.1; 68.2] versus 53.7% [32.2; 71.1](P 0.49) in patients with GIS <42 or >+ 42, 59.7% [44.5; 71.9] versus 48.2% [29.7; 64.5] (p 0.24) in > median GIS at 35 or >= median GIS at 35, 59.1% [46.0; 70.0] versus 38.9% [15.0; 62.5] in > 3rd quartile GIS at 55 or >= 3rd quartile GIS at 55 (p 0.14), or 54.2% [41.5; 65.2] versus 57.7% [37.0; 73.7] (p 0.11) in patients with and without BRCA mutation, respectively.

Conclusion There was no survival difference according to the type of genetic anomaly or the GIS score. The study is limited by a short follow-up period and may hinder survival differences over time. Not all HRD patients received PARP inhibitors.

Disclosures -