Androgen receptor mRNA expression is a predictor for recurrence-free survival in non-muscle invasive bladder cancer

Non-muscular invasive bladder cancer (NMIBC) has a high risk of recurrence. As androgen receptor (AR) reportedly affects bladder cancer, we assessed the correlation between NMIBC recurrence and tumor AR expression in Japanese patients.

We retrospectively reviewed 53 specimens of non-metastatic NMIBC, with recurrence-free survival (RFS) as the primary endpoint. We used real-time quantitative polymerase chain reaction to quantify AR mRNA expression. Kaplan-Meier product-limit estimators were used to assess RFS distribution, log-rank tests to analyze differences in RFS between high- and low-risk groups; and multivariate analyses of AR mRNA expression and other clinicopathological factors to predict independent factors for RFS.

The high AR mRNA-expressing group (n = 43) tended to have a longer median RFS (not reached) than did the low-AR group (n = 10; 9.04 months; P = 0.112). Multivariate analysis showed female sex (hazard ratio [HR]: 7.360, 95% CI: 1.649-32.856, P = 0.009), tumor size ≥3 cm (HR: 23.697, 95% CI: 4.383-128.117, P < 0.001) and low AR mRNA expression (HR: 0.202, 95% CI: 0.048-0.841, P = 0.028) to be independent predictors of shorter RFS.

Our study showed that low AR mRNA expression level is an independent risk factor for RFS in Japanese patients with NMIBC. Further studies are necessary but AR expression might be a new indicator of recurrence of NMIBC.