Introduction/Background Homologous recombination deficiency (HRD) prevents the repair of gene damage caused by DNA-damaging agents such as platinum-based chemotherapy, disrupts the ability to homologous recombination (HR), and further causes gene instability. Germline (g)/somatic(s) BRCA1/2 are the most common cause of HRD. BRCA protein is a type of DNA double-strand damage repair protein encoded by the BRCA gene. BRCA1/2 is a susceptibility gene for both breast and ovarian cancer. The aim of this study is to established the frequency of HRD according to the histological subtype ovarian cancer at single oncogynecology center.

Methodology This retrospective study was conducted at Department of Gynecology, Military Medical Academy, Sofia (2021 – 2023 years) and included 27 ovarian cancers (III – IV, FIGO stages) patients aged 36 – 68 years. Radical or cytoreductive surgical treatment was performed in all patients and ovarian cancer was confirmed by pathology.

Tumor samples of all patients included was tested by Myriad MyChoice® CDx test (Myriad Genetic Laboratories, Inc. Salt Lake City, UT). This test identifying ovarian cancer patients with positive homologous recombination deficiency (HRD) status by detecting BRCA1 and BRCA2 (sequencing and large rearrangement) variants and assessing genomic instability with 3 biomarkers: loss of heterozygosity, telomeric allelic imbalance and large-scale state transitions

Results Our results show 70.3% patients without HRD and 29.7% with HRD, with the most common histological type of ovarian carcinoma in which it occurs is High grade serous carcinoma

Conclusion HRD status and frequency are important for postoperative therapy of women with ovarian cancer, as well as for survival and mortality indicators.

Disclosures We have nothing to disclosures