Androgen Receptor As A Predictive Marker Of Response To Neoadjuvant Chemotherapy In Locally Advanced Breast Carcinoma

Abstract

Background: Androgen receptor (AR) expression in breast cancer has gained interest as a  potential biomarker for predicting treatment response. This study evaluated AR expression as a predictive marker for pathological complete response (pCR) following neoadjuvant chemotherapy in locally advanced breast carcinoma.

Methods: A prospective observational study was conducted on 268 patients with locally advanced breast cancer receiving neoadjuvant chemotherapy. Immunohistochemical analysis was performed to determine AR status. The primary endpoint was pathological complete response (RCB-0) correlation with AR expression. Secondary endpoints included associations between AR status and clinicopathological features.

Results: Among 268 patients, 60.4% (n=162) were AR-positive. The overall pCR rate was 22.0% (n=59). AR-negative patients demonstrated significantly higher pCR rates compared to AR-positive patients (28.3% vs 17.9%, p=0.047). In triple-negative breast cancer subgroup (n=62), AR-negative status was strongly associated with higher pCR (50.0% vs 21.4%, p=0.021). Subgroup analysis of HER2-negative tumours (score 0) showed AR-negative patients achieving 34.5% pCR versus 16.1% in AR-positive patients. Similarly, in HER2-low expressing tumours, AR-negative patients demonstrated 26.7% pCR compared to 4.3% in AR-positive cases. AR-positive patients showed greater estrogen receptor positivity (p<0.001) and lower histological grade (p=0.021).

Conclusion: AR expression status serves as a significant predictive biomarker for neoadjuvant chemotherapy response in HER-2 negative breast cancer, particularly in TNBC subtype. AR-negative patients achieve higher pCR rates across HER2-negative and HER2-low subtypes, suggesting potential utility in treatment stratification and personalized therapeutic approaches.