The prognostic role of androgen receptor in patients with early stage breast cancer: A meta-analysis of clinical and gene expression data

Androgen receptor (AR) expression has been observed in about 70% of breast cancer (BC) patients, but its prognostic role remains uncertain. Methods: To assess the prognostic role of AR expression in early-stage BC we performed a meta-analysis of studies that evaluated the impact of AR at the protein and gene expression level on disease free survival (DFS) and/or overall survival (OS). Eligible studies were identified by systematic review of electronic databases using the MeSH-terms "breast neoplasm" and "androgen receptor" and were selected after a qualitative assessment based on the REMARK criteria. A pooled gene expression analysis of 35 publicly available microarray data sets was also performed from patients with early-stage BC with available gene expression and clinical outcome data. Results: 22 out of 33 eligible studies for the clinical meta-analysis, including 10.004 patients, were considered as evaluable for the current study after the qualitative assessment. AR positivity defined by IHC was associated with improved DFS in all BC patients [multivariate (M) analysis, HR 0.46, 95% CI 0.37-0.58, p<0.001] and better OS [M-HR 0.53, 95% CI 0.38-0.73, p<0.001]. 35 datasets including 7.220 patients were eligible for the pooled gene expression analysis. High AR mRNA levels were found to confer positive prognosis overall in terms of DFS (HR 0.82 95%CI 0.72-0.92; p=0.0007) and OS (HR 0.84 95%CI 0.75-0.94; p=0.02) only in univariate analysis. Conclusion: Our analysis, conducted among more than 17.000 women with early-stage BC included in clinical and gene expression analysis, demonstrates that AR positivity is associated with favourable clinical outcome.