Radical Cystectomy after BCG Immunotherapy for High-Risk Nonmuscle-Invasive Bladder Cancer in Patients with Previous Prostate Radiotherapy

Impact of prostate cancer radiotherapy on the biological behavior and specific mortality of subsequent bladder cancer

BACKGROUND

The impact of different radiotherapy modalities on the development and characteristics of second primary bladder cancers (BCa) and BCa-specific mortality (BCa-SM) remains unclear. Thus, we evaluated the incidence and biological behavior of subsequent BCa and related survival in patients who underwent radiation therapy for prostate cancer (PCa).

METHODS

A total of 530,581 patients in the surveillance, epidemiology, and end results database with localized PCa between 1988 and 2013 were identified. PCa treatments included radical prostatectomy (RP), external beam radiotherapy (EBRT), radioactive implants (RI), and combined EBRT and RI (EBRI). A multivariable competing risk analysis based on a proportional sub distribution hazards model was used to determine the impact of different radiotherapy modalities on BCa incidence and specific mortality.

RESULTS

Incidence of BCa was significantly high in patients treated with EBRT, RI, and EBRI vs. RP [sub distribution hazard ratio (SHR) 1.41, P < 0.001; SHR 1.58, P < 0.001; SHR 1.56, P < 0.001, respectively]. BCa following EBRT, RI, and EBRI were more commonly non-urothelial (3.3%, 2.9%, 3.3%, respectively, versus 1.2%) and T4 (3.5%, 6.1%, 5.0%, respectively, versus 1.6%) compared with RP. RI associated with a higher rate of BCa metastasis than RP (2.6% vs. 1.1%). Prior EBRT, RI, and EBRI increased BCa-SM (SHR 1.44, P = 0.001; SHR 1.21, P = 0.047; and SHR 1.42, P = 0.032, respectively).

CONCLUSIONS

Patients receiving radiotherapy for PCa have a higher risk of BCa. BCa after EBRT, RI, and EBRI is more likely to be non-urothelial, stage T4, and with increased BCa-SM. Prior RI associated with a higher rate of BCa metastasis.

Immune therapies in non-muscle invasive bladder cancer

OPINION STATEMENT

Non-muscle invasive bladder cancer (NMIBC) continues to be a challenging disease to manage. Treatment involves transurethral resection and, often, intravesical therapy. Appropriate patient selection, accurate staging, and morphological characterization are vital in risk-stratifying patients to those who would most benefit from receiving intravesical therapy. Bacillus of Calmette and Guérin (BCG) continues to be the first-line agent of choice for patients with intermediate- and high-risk NMIBC. Treatment should begin with the standard induction course of 6 weekly treatments. The inclusion of subsequent maintenance courses of BCG is imperative to optimal therapeutic response. While patients with intermediate-risk disease should receive 1 year of maintenance therapy, high-risk patients benefit from up to 3 years of maintenance therapy. BCG use should not be used in low-risk patients with de novo Ta, low-grade, solitary, <3-cm tumors. Conversely, patients with muscle-invasive disease should forgo intravesical immunotherapy and proceed directly to radical cystectomy. Cystectomy also should be considered in patients with multiple T1 tumors, T1 tumors located in difficult to resect locations, residual T1 on re-resection, and T1 with concomitant CIS. Although promising new immunotherapeutic agents, such as Urocidin, protein-based vaccines, and immune check point inhibitors are undergoing preclinical and clinical investigation, immunotherapy in bladder cancer remains largely reliant on intravesical BCG with surgical consolidation as the standard salvage treatment for patients with BCG failure.