Bladder outlet obstruction (BOO) in men with castration-resistant prostate cancer

To evaluate the frequency of bladder outlet obstruction (BOO) and detrusor overactivity (DO) in patients with castration-resistant prostate cancer (CRPC) and lower urinary tract symptoms (LUTS).

Our prospective urodynamics database was queried. Inclusion criteria were CRPC and an International Prostate Symptom Score (IPSS) ≥ 20. Exclusion criteria were previous local therapy to the prostate gland, known urethral stricture disease, and a neurological component of LUTS. Twenty-one patients were identified. Urodynamic findings were analysed and compared with those of a matched cohort of 42 patients with benign prostatic enlargement (BPE).

The median age of patients in the CRPC group was 74 years, and the median prostate-specific antigen (PSA) level at the time of the urodynamic study was 90 ng/mL. According to the BOO index, three patients (14%) were obstructed, three were equivocally obstructed (14%) and 15 were unobstructed. DO was seen in 12 patients (57%). Compared with the BPE group, patients with CRPC had lower cystometric bladder capacities (P = 0.003), were less likely to have BOO (14 vs 43%, P = 0.009) and more likely to have DO (57 vs 29%, P = 0.028).

This study generates the hypothesis that only a minority of CRPC patients with LUTS have BOO, and that more than half of patients have DO. LUTS in CRPC may therefore be seldom attributable to BOO, but are, at least in part, related to DO and reduced cystometric capacity. A urodynamic investigation may be necessary before palliative transurethral resection of the prostate to select appropriate candidates. Larger prospective studies are needed to confirm our findings.