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.