Effect of Bacille Calmette-Guérin for Non-Muscle-Invasive Bladder Cancer After Prostate Radiotherapy

Abstract

Background: Little is known about the impact of prior prostate radiation therapy (RT) on the Bacille Calmette-Guerin (BCG) immunotherapy response in patients with non-muscle invasive bladder cancer (NMIBC).

Objective: We hypothesized that the damaging radiation effects on the bladder could negatively influence BCG efficacy.

Methods: Men with a history of high-risk NMIBC were identified within the Surveillance, Epidemiology, and End Results-Medicare database. All patients completed adequate BCG defined as at least 5 plus 2 treatments completed within 12 months. Patients were stratified into 2 groups: with prior RT for prostate cancer and without prior RT before the diagnosis of NMIBC. The primary endpoint was a 5-year composite for progression defined as disease progression requiring systemic chemotherapy, checkpoint inhibitors, radical or partial cystectomy, or cancer-specific death.

Results: We identified 3,466 patients with NMIBC, including 145 with prior RT for prostate cancer. Five-year progression occurred in 471 patients (13.6%). Patients with prior RT were older than patients without prior RT (77.0 vs 75.0 years; P < .001). The distribution of T stage was significantly different at diagnosis between the RT and non-RT groups (RT: Ta, 44.8%; Tis, 18.6%; T1, 36.6%; without RT: Ta, 40.9%; Tis, 10.8%; T1, 48.3%; P = .002). No difference in the risk of total progression was observed between patients with and without prior RT (P = .67). Similarly, no difference was observed after multivariable adjustment (hazard ratio, 0.99; 95% CI, 0.61-1.58; P = .95).

Conclusion: For patients with NMIBC who undergo adequate BCG treatment, prior RT for prostate cancer was not associated with worse 5-year progression-free survival.

Keywords: Bacille Calmette-Guérin; bladder cancer; outcomes; prostate cancer; radiation therapy.

Fig. 1

Flowchart for Identifying Patients in SEER Database with NMIBC and Adequate BCG Therapy With and Without a History of RT for Prostate Cancer. BCG indicates bacille Calmette-Guérin; ESRD, end-stage renal disease; HMO, health maintenance organization; NMIBC, non–muscle-invasive bladder cancer; RT, radiation therapy; SEER, Surveillance Epidemiology and End Results.

Fig. 2

Cumulative Incidence Function of 5-Year Progression of NMIBC With Corresponding Plots at Each Time Point. A, NMIBC group. B, AJCC T stage. AJCC indicates American Joint Committee on Cancer; NMIBC, non–muscle-invasive bladder cancer; PCa, prostate cancer; RT, radiation therapy.