STUDY OF PREDICTIVE VALUE OF RAD51 EXPRESSION FOR THE EFFECTIVENESS OF PLATINUM-BASED THERAPY OF HIGH-GRADE SEROUS OVARIAN CARCINOMA.

The search for novel markers of predictive significance is an important issue in the management of ovarian cancer (OC) patients. Recently, the expression of the RAD51 protein, involved in homologous DNA repair has been shown to be predictive of platinum chemotherapy response in OC patients. To establish the relationship between the level of RAD51 protein expression in patients with high-grade serous ovarian carcinoma (SOC) after neoadjuvant platinum chemotherapy and the frequency of recurrence, disease progression, and relapse-free survival. RAD51 status was assessed in the archival histological material of 30 patients with SOC of stage III who received perioperative platinum-based chemotherapy. RAD51 expression was analyzed using a double-staining technique in samples containing at least 100 geminin-positive tumor cells. RAD51 status was considered positive if > 10% of geminin-positive nuclei were positive for RAD51. In 16 of 30 cases, the tumor had a RAD51-positive status (homologous repair proficient, HRP), and in 14 - RAD51-negative (homologous repair deficient, HRD). We found that the risk of disease progression in patients with RAD51 HRP status was 3.42 times higher compared to patients with RAD51 HRD status (HR = 3.42; 95% CI 1.38-8.46; p = 0.008). In SOC patients with RAD51 HRP status, a significantly higher (p < 0.001) rate of disease progression over 3 to 12 months of postoperative observation compared to patients with RAD51 HRD status was detected. RAD51 expression is predictive for the response of highgrade SOC to platinum therapy.