Pathological complete response (pCR) after neoadjuvant chemotherapy (NAC) for advanced breast cancer patients with high risk for Hereditary Breast and Ovarian Cancer Syndrome (HBOC).

Abstract

e13549 Background: Local Advanced Breast Cancer (LABC) is associated with high risk of death. NAC is a safe and effective approach for these populations. pCR is a proven prognostic factor in several studies of NAC. HBOC is associated to high risk of breast cancer usually in young age and especially for BRCA1 mutations with a basal phenotype. The aim of this study was to evaluate the influence of BRCA mutational status on frequence of pCR. Methods: this is part of a retrospective, observational study of prevalence of HBOC among patients admitted for cancer therapy in our institution. Since August, 2018 over 300 pte suspected for HBOC (by NCCN criteria) have been screened for NGS with a 31-gene painel. Statistical analysis performed Person X2/Fisher and logistic regression ( p< 0.05; SPSS 20.0). Results: Most pte were women (80%), with median age of 38y (22-72y), most tumors were (80%) stage III, Luminal B (23%) and TNBC (36%). Pathogenic mutations were identified in 34%(n = 28) of the sample ( BRCA1 50%, BRCA2 16.7%, PALB2 16.7%, follow by TP53, PMS2, XRCC2, MUTYH, BARD1 and ATM with 2.8% each).The majority of patients had more than 1 NCCN criteria: age < 45y (83%), family member with BC < 50y (24%) or TNBC (33%) the most common. TNBC tumors had stronger association with germline mutation ( p< 0.001). Regarding response rate there were 13 stable disease (SD), 5 progressive disease (PD), 43 pCR and 39 pathological partial response (pPR). There were no differences in pRC among mutated or no mutated pte, p= 0,170. However, among mutated TNBC there were strong correlation with more pCR, p< 0,006. There was no difference on pCR rate related to mutation status (BRCA vs Non-BRCA), p = 0,84. Conclusions: the present study corroborates other data about the impact of germline mutation status over pCR after NAC for LABC, except for mutated TNBC population, whose seems to be more NAC sensitive.