Abstract 3474: Prevalence of BRCA1 and BRCA2 small mutation and large genomic rearrangements in breast cancer patients visiting a genetic counseling clinic

Abstract

Abstract BACKGROUND: This study was conducted to investigate mutation prevalence of the BRCA1 and BRCA2 genes in breast cancer patients, including both small mutations and large genomic rearrangements (LGRs) following the patients in the process of genetic counseling. METHODS: A total of 358 breast cancer patients who visited genetic counseling clinic and screened for BRCA1/2 mutation at the National Cancer Center were included. Among the non-carriers by direct sequencing, a subset of patients who were agreed on participation of the research were screened for the presence of LGRs using a multiple ligation-dependent probe amplification (MLPA) assay. Clinico-pathologic characteristics of cancer were evaluated thorough medical record review and characteristics for those who found BRCA mutation through MLPA were described. RESULTS: 53 (14.8%) mutation carriers were identified. The frequency of BRCA small mutations in specific subgroups was as follows: 18.0% of patients with a family history, 12.8% of early-onset breast cancer, and 20.6% of bilateral breast cancer patients. MLPA identified BRCA1 LGRs in 3 (1.5%) out of 204 patients with BRCA1 and BRCA2 small mutation-negative results. Those with LGRs showed higher probabilities of BRCA mutation carriers estimated by risk assessment models and receptor negatives of tumor immunohistochemistry. CONCLUSIONS: The prevalence of BRCA1/2 mutation prevalence in breast cancer patients with family history or personal risk factors were comparable to previous Korean studies. MLPA to screen for mutations in the BRCA1 gene could be recommended for breast cancer patients negative for small mutations. To specify proper targets of MLPA, probabilities of carrying BRCA1/2 mutation and tumor receptor status could be considered. Citation Format: Ji Yeon Sohn, Boyoung Park, Kyong-Ah Yoon, Soo Jin Park, Moo Hyun Lee, Eun Hae Cho, Keun Seok Lee, Myong Cheol Lim, Sun-Young Kong, Eun Sook Lee. Prevalence of BRCA1 and BRCA2 small mutation and large genomic rearrangements in breast cancer patients visiting a genetic counseling clinic. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3474.