Clinical outcomes of BCG infections in patients undergoing intravesical immunotherapy for non-muscle-invasive bladder cancer: a systematic review and meta-analysis.

Abstract

Introduction: Intravesical bacillus Calmette-Guérin (BCG) is the standard treatment for high- and intermediate-risk non-muscle-invasive bladder cancer (NMIBC). Despite its 50-year history of use, there remains a paucity of data regarding infections associated with intravesical BCG immunotherapy in real-world clinical practice. Thus, this study aimed to assess the clinical outcomes of BCG infections in a high-volume center and systematically review the literature on the topic.

Evidence acquisition: We retrospectively reviewed the records of patients who had experienced BCG infections following intravesical immunotherapy for NMIBC at our institution between 2001 and 2022, and systematically reviewed the literature following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) (PROSPERO registration: CRD42024497171). The PubMed, EMBASE and Scopus databases were searched in December 2023. Endpoints were: overall incidence of BCG infections, incidence of disseminated infection and mortality.

Evidence synthesis: Twelve eligible references were identified through the search strategy (n=306 patients), while our series comprised 18 patients. A total of 324 patients were thus included for evidence synthesis. Meta-analysis results showed that the pooled incidence of BCG infection among patients treated with intravesical immunotherapy was 2% (95% CI 1-2%). The pooled mean age was 71.19 years (95% CI 65.89-76.50). The pooled mean duration of intravesical therapy until the diagnosis of BCG infection was 11.67 months (95% CI 4.62-18.71), and a low rate of urine culture positivity was observed (pooled rate of 23% [95% CI 13-34%]). Disseminated disease was present in 61% of cases (95% CI 45-77%), while the pooled rate of local (genitourinary) involvement was 32% (95% CI 17-50%). The proportion of deaths among these patients was 5% (95% CI 2-10%).

Conclusions: BCG infections following intravesical immunotherapy are a rare condition (2%). While more than half of those who experience this complication present with a disseminated pattern, the associated mortality appears to be low (5%).