Frequency of BRCA1/2 mutations and the immunological profile of triple-negative breast cancer in young women: a systematic review

Abstract

Triple-negative breast cancer (TNBC) in women ≤40 years old is characterized by aggressive behavior, a high frequency of BRCA mutations, and limited therapeutic options. The purpose of this study was to systematically review data on BRCA1/2 mutations and PD-L1 expression in young women with TNBC to assess molecular and clinical features. The review included seven studies from China, South Korea, Portugal, Mexico, Arab countries, and Russia (2015–2024), covering a total of 3,939 patients. For the systematic review of BRCA mutation frequency, a subgroup of women ≤40 years old (n = 355) was analyzed. A Russian study was included for the systematic review of PD-L1 expression. The study found that nearly one in five young patients with TNBC carried BRCA1/2 mutations (18.9%; 95% CI 15.1–23.3%), predominantly BRCA1. These mutations were associated with aggressive disease, early onset, and a high risk of contralateral breast cancer. Additionally, a high proportion of PD-L1-positive tumors (37.9%) indicates that a significant subset of patients may benefit from immune checkpoint inhibitors. These findings underscore the need for comprehensive molecular and immune profiling of young women with TNBC and highlight the importance of further multicenter studies in this age group.