BCG Administration after Prior Radiation Treatment for Prostate Cancer

Prostate radiotherapy is associated with worse oncologic outcomes in patients with bladder cancer. The underlying mechanism is incompletely understood but is thought to be related to an altered microenvironment promoting tumorigenesis. However, there is a gap in the literature regarding how the effect of BCG varies according to prior radiotherapy in patients with non-muscle invasive bladder cancer (NMIBC). In this context, we sought to evaluate oncologic outcomes in NMIBC patients who have previously undergone prostate radiotherapy compared to patients with no prior history of pelvic radiotherapy.

This is a retrospective cohort study that includes all patients who received intravesical for NMIBC at our institution from 2001 to 2019. Patients were stratified into 3 cohorts: prior radiotherapy (RT), radical prostatectomy (RP), and no prostate cancer (No PCa). The outcomes of interest were recurrence at 1-year, progression to muscle-invasive bladder cancer (MIBC), and progression to metastatic disease. Comparisons were also made between cohorts with respect to elapsed time from radiation therapy. Wilcoxon rank-sum test was used for comparing continuous variables, while χ² and Fischer's exact tests were used to examine categorical variables.

In 199 total patients who underwent BCG for NMIBC, 23 had a prior history of prostate radiotherapy treatment, while 17 underwent prior radical prostatectomy. Overall, 41.2% of patients had recurrence at 1 year. There was no difference in the number of induction or maintenance BCG administrations received between the cohorts within the first year. There was no significant difference in recurrence at 1 year between the 3 cohorts (P = .56). There was also no difference in progression to MIBC or progression to metastatic disease with P = .50 and 0.89, respectively.

The risk of recurrence after induction BCG treatment for high-grade NMIBC does not vary according to prior radiation treatment for prostate cancer.