Frequency of germline DNA genetic findings in an unselected prospective cohort of triple-negative breast cancer patients participating in a platinum-based neoadjuvant chemotherapy trial

Abstract

We describe the status and frequency of germline DNA genetic findings in an unselected prospective cohort of triple negative breast cancer patients participating in a platinum-based neoadjuvant chemotherapy trial. Study population includes 124 consecutive patients with stage II-III TNBC from a trial exploring the antitumor activity of neoadjuvant carboplatin/docetaxel chemotherapy enrolled between 2012 and March 2015, to determine the frequency of germline DNA genetic mutations. 17.1 % of the patients with germline DNA tested had deleterious mutations in any of the analyzed genes (12.38 % in BRCA1, 1.9 % in BRCA2 and BARD1 and 0.95 % in RAD51D). Attending the intrinsic subtype, all the BRCA1/2 carriers tested had basal-like subtype. Among wild-type (WT) patients, 70.11 % had basal subtype, 16.09 % HER2 enriched, 1.15 % Luminal B, and 4.60 % Normal-like. Mean age at diagnosis was significantly lower in mutation-carriers compared with no carriers (43.72 vs 53.10, p = 0.004). 3 BRCA1/2 carriers were detected between 51 and 60 years, and only one deleterious mutation (BARD1) over 60 years. A positive familiar history of breast and ovarian cancer was more frequent in patients with deleterious mutations (39.39 vs 17.94 %, p = 0.043). Our study confirms the prevalence of BRCA1/2 mutations in TNBC patients. TNBC should therefore be considered by itself as a criterion for BRCA1/2 genetic testing. Determination of other breast cancer predisposition genes implicated in homologous recombination should also be discussed in this population. However, no definitive conclusions can be reached due to the low prevalence and the uncertain clinical impact of most of the genes included.

Keywords: BRCA1; BRCA2; Carboplatin; Genes; Germline DNA; Triple-negative breast cancer.