Loss of androgen receptor expression is not associated with pathological stage, grade, gender or outcome in bladder cancer: a large multi-institutional study

OBJECTIVE To investigate androgen receptor (AR) expression in a large series of patients with bladder cancer (BC) because data on a limited number of patients showed that loss of AR expression was associated with invasive BC. PATIENTS AND METHODS A total of 472 patients with urothelial bladder carcinoma (UBC) from two institutional centres (Toronto and Dallas) were analysed. Tissue microarrays comprising both non-muscle-invasive UBC (n = 167) and muscle-invasive UBC (n = 305) were accrued and immunohistochemical staining for AR was performed. We used bright-field microscopy imaging coupled with advanced colour detection software to detect, classify and count stained cellular objects and manual scoring. Results obtained in Dallas were blindly reviewed and validated in Toronto and samples randomly chosen were further analysed in Rochester, NY, USA. RESULTS The AR were positively expressed in 61/472 (12.9%) bladder tumours. No statistically significant difference in AR expression between men and women was observed. Only 9.0% of non-muscle-invasive BC expressed the AR compared with 15.1% of muscle-invasive tumours (P = 0.059). The highest percentage of AR positivity (28.9% of cases) was found in T2 tumours. There was no statistically significant difference in death from BC, time to death, or time to recurrence between AR-positive and AR-negative cases. CONCLUSION In contrast to previous reports, based on our large BC series, we did not observe a decrease in AR protein expression in bladder tumours with increased pathological stage. Our data do not suggest that loss of AR expression is gender-related nor is it associated with invasive BC.