Alternating intravesical instillation of Bacillus Calmette-Guérin and Pseudomonas aeruginosa effectively prevents postoperative recurrence in high-risk non-muscle-invasive bladder cancer.

Objective: To evaluate the role of alternating intravesical instillation of Bacillus Calmette-Guérin (BCG) and Pseudomonas aeruginosa (PA) in preventing postoperative recurrence in high-risk non-muscle-invasive bladder cancer (HR-NMIBC).

Methods: We retrospectively reviewed the clinical data from 115 HR-NMIBC cases who underwent transurethral resection of bladder tumors (TURBT) at Gongli Hospital of Shanghai Pudong New Area between March 2021 and January 2023. Patients were grouped based on postoperative management: a control group (n=51) treated with standard gemcitabine instillations and an intervention group (n=64) given alternating BCG and PA instillations. This study assessed 1- and 2-year recurrence, recurrence-free survival, safety (gastrointestinal reactions, fever, bladder irritation symptoms, and hematuria), serum tumor markers, and life quality. Univariate and multivariate Cox proportional hazards analyses were applied to identify the recurrence predictors. A nomogram predictive model was further developed for postoperative recurrence risk estimation, and its performance was later validated.

Results: Despite an equivalent 1-year recurrence rate, the intervention group showed a lower 2-year recurrence rate, prolonged recurrence-free survival, and superior safety (fewer adverse events) than controls. The intervention group also showed decreased post-treatment serum tumor marker concentrations and greater life quality enhancement relative to the control cohort. Univariate and multivariate analyses identified tumor number ≥3 (P=0.036), high-grade tumors (P=0.040), and gemcitabine monotherapy (P=0.035) as independent predictors for 2-year recurrence. The nomogram's scoring system reliably associated elevated risk points with heightened recurrence risk, demonstrating strong discrimination and reliable calibration in medium-to-high-risk ranges.

Conclusions: Alternating intravesical BCG and PA instillations markedly decreases 2-year postoperative recurrence on the premise of favorable safety in HR-NMIBC patients.