Abstract
Quadruple-negative breast cancer (QNBC) is a subgroup of triplenegative breast cancer (TNBC) that lacks androgen receptor (AR) expression. While TNBC patients with AR expression have shown a promising response to AR-targeted therapies, QNBC patients’ treatment options remain limited, with no targeted therapy. We investigated the biomarker profiles of large cohorts of AR+TNBC and QNBC to identify their molecular differences.