Assessing the prognostic role of androgen receptor expression in non-metastatic triple-negative breast cancer

Background Triple negative breast cancer (TNBC) represents 15-20% of all invasive breast cancer with poor breast cancer survival. Androgen receptor (AR) expression in TNBC shows significant variability in the literature, with rates ranging from 7% to 75%. The association between AR expression and prognosis in TNBC remains controversial. Methods A comparative retrospective design was utilized including all TNBC cases between 2014-2020. AR receptor expression was evaluated by immunohistochemical staining using whole tissue sections from archived paraffin-embedded formalin fixed blocks. Correlation of AR expression with standard clinical pathological factors and clinical outcomes of interest were assessed; including disease free survival (DFS), breast cancer specific survival (BCSS), and overall survival (OS). Results 149 patients with non-metastatic TNBC were included. 94 patients (63.3%) being AR negative and 55 patients (36.7%) were AR positive. No statistical difference in tumor characteristics between the two groups was found. The 5-year OS rates for AR negative and positive patients were 60% and 70% respectively (p= 0.021). However, this statistical significance was lost with longer follow-up (103 months, p=0.25). The 5-year DFS was similar for both groups (AR negative and AR positive, 64.3%, 62.9% respectively, p=0.39) in addition to the BCSS (73%, 78.8% respectively, p= 0.84). In univariable and multivariable analyses, AR expression did not significantly impact OS or DFS (HR: 0.71 and 1.07, p= 0.3, 0.8, respectively). Conclusion In this study, AR status showed no association with DFS, BCSS, or OS; and was not a prognostic factor in TNBC. Further studies exploring the role of AR in TNBC are warranted as AR expression could be a potential target with antiandrogen therapy.