Androgen Receptor Expression and T-Lymphocyte Infiltration as Prognostic Indicators in Triple-Negative Breast Cancer: A Retrospective Study

Background: Triple-negative breast cancer (TNBC) is a biologically heterogeneous disease. Clinically accessible biomarkers remain limited. Objective: To evaluate androgen receptor (AR) expression and immune response—stromal tumor-infiltrating lymphocytes (sTILs), CD4+, CD8+, CD4/CD8 ratio—to explore their clinicopathological associations and relationships with 3-year overall survival (OS) in TNBC. Methods: We retrospectively analyzed data from 86 treatment-naïve women with TNBC who were treated between 2012 and 2019 at a single academic center. AR and CD4/CD8 were assessed immunohistochemically; sTILs were scored on H&E following The International TIL Working Group recommendations. Survival analyses focused on 3-year OS, with follow-up truncated at 36 months and multivariable Cox regression restricted to non-metastatic disease (stage I–III). Results: High AR expression (≥10%) occurred in 23% of tumors and was associated with lower CD8+ infiltration and lower tumor grade. Across adjusted models, we did not demonstrate statistically significant and independent associations between AR or immune markers and 3-year OS; however, inference is limited by the low number of events (10 deaths). Conclusions: AR status was associated with the immune response, particularly with reduced CD8+ infiltration in AR-high tumors, supporting the concept of biologically distinct AR–immune phenotypes. The absence of statistically significant survival associations in adjusted analyses should be interpreted cautiously given the limited event counts, and larger prospective cohorts are needed to validate prognostic and potential therapeutic implications.