Androgen receptor expression and outcome of neoadjuvant chemotherapy in triple-negative breast cancer

OBJECTIVE: Triple-negative breast cancers (TNBC) include a heterogeneous group of diseases, characterized by the lack of estrogen receptor (ER), progesterone receptor (PgR), and human epidermal growth factor receptor 2 (HER2) expression. TNBC that shows an overexpression of the androgen receptor (AR) defines the phenotype known as "luminal androgen receptor" (LAR), while the absence of the AR defines a "quadruple negative breast cancer" (QNBC). Several reports have associated AR positivity with a lower response to neoadjuvant chemotherapy (NAC), while divergent data have been reported about the impact of AR positivity on survival. The aim of this study was to retrospectively review our series of patients with TNBC tested for AR and submitted to NAC and compare pathologic complete response (pCR) rates in patients with a LAR phenotype or with QNBC. PATIENTS AND METHODS: The clinical records of all patients with TNBC tested for AR that underwent NAC at our Institution from January 1. 2015 to June 30, 2019 were reviewed. Histopathological features as well as ER, PgR, Ki67, HER2 values, clinical and pathological stage. and results of BRCA gene expression profiling were registered for all patients. RESULTS: Of the 145 TNBC patients treated by NAC, 20 (13.8%) had a LAR phenotype, while 125 (86.2%) had a QNBC. Overall, a pCR was achieved in 52 patients (35.8%). Patients with LAR phenotype had a lower rate of pCR as compared to patients with QNBC phenotype (25% vs. 37.6%). High Ki67 values (>50%) were observed less frequently in patients with a LAR phenotype (50% vs. 76.8% in QNBC). CONCLUSIONS: Our data seem to confirm that the LAR phenotype is associated to lower rates of pCR after neoadjuvant chemotherapy: routine assessment of AR expression in addition to classical biomarkers in patients with TN-BC could help to better personalize treatment.