Prevalence of BRCA1 and BRCA2 Genes Mutations and Their Impact on Treatment Strategies in Women with Breast and/or Ovarian Cancer

Author: Justas Krištopaitis Title: Prevalence of BRCA1 and BRCA2 genes mutations and their impact on treatment strategies in women with breast and/or ovarian cancer Aim: To determine the frequency of BRCA1/2 genes mutations in women with breast and/or ovarian cancer and to assess their treatment tactics. Objectives: 1. To evaluate the frequency of BRCA1, BRCA2 gene mutations among genetically studied women with breast cancer. 2. To evaluate the frequency of BRCA1, BRCA2 genes mutations among genetically studied women with ovarian cancer. 3. To assess the impact of BRCA1 and BRCA2 genes mutations on the scope of surgery in breast cancer patients. 4. To assess the impact of BRCA1 and BRCA2 gene mutations on the choice of chemotherapy regimen in breast cancer patients. Methods: A retrospective cohort study was performed at the institute of Oncology in LSMU MA MF. The study assessed the prevalence of BRCA1 and BRCA2 genes mutations in the study group and the impact of BRCA1/2 on the choice of treatment tactics - scope of surgery, neo/adjuvant chemotherapy regimen. The statistical data analysis was performed using SPSS 20.0 program. Participants: 255 patients diagnosed with breast and/or ovarian cancer, who were consulted by a geneticist and had genetic testing for BRCA1 and BRCA2 genes germinal mutations at LSMU Kaunas clinics in 2017 year. Results: 58 patients had ovarian cancer (22,7 %), 206 - breast cancer (80,2 %), of which 4,4 % was simultaneously diagnosed with ovarian cancer. Frequencies of germinal mutations among breast cancer patients: BRCA1 - 13,4 %, BRCA2 - 3,4 %; among ovarian cancer subjects: BRCA1 – 17,2 %, BRCA2 – 1,7 %. The most frequently identified BRCA1/2 genes mutations in breast cancer patients - 4153delA (29,4 %), 5382insC (26,5 %), c.658_659del (11,8 %), 300T>G (8,8 %) and in ovarian cancer patients -4153delA (45,5 %), 5382insC (27,3 %). The choice of bilateral mastectomy and bilateral breast-conserving surgery was influenced by the discovery of the BRCA1/2 mutations (p<0,001, p=0,004, respectively), by bilateral breast cancer diagnosis (p<0,001, respectively). There was a statistically significant association between BRCA1/2 genes mutations and TAC neo/adjuvant chemotherapy (p = 0,003). Conclusions: 1. BRCA1 and BRCA2 genes mutations were detected in 16,5 % patients diagnosed with breast cancer. 2. BRCA1 and BRCA2 genes mutations were detected in 18.9 %. patients diagnosed with ovarian cancer. 3. A statistically significant association was found between bilateral mastectomy, bilateral breast-conserving surgery and BRCA1 and BRCA2 genes mutations (p