To determine whether asymptomatic bacteriuria (ABU) prior to Bacillus Calmette-Guérin (BCG) immunotherapy has an impact on the oncological results and overall tolerability of BCG treatment in patients with non-muscle-invasive bladder cancer (NMIBC).

We analyzed retrospectively all patients who received ≥ 1 BCG instillations as treatment of NMIBC in Helsinki University Hospital and Turku University Hospital during 2009-2018. Patients submitted urine specimen 1-7 days prior to the initiation of BCG therapy. ABU was classified as having any positive urine culture but no dysuria or fever. Our primary endpoints were 5-yr recurrence-free survival and progression-free survival. Discontinuation rate of BCG therapy was a secondary endpoint.

We identified 795 patients, of whom 154 (19%) had ABU prior to the first BCG instillation. The 5-yr recurrence-free survival rates in the uninfected and bacteriuric groups were 63% (95% confidence interval [CI]: 59-67%) vs. 69% (95% CI: 62-78%), respectively (hazard ratio [HR] 0.83, 95% CI 0.60-1.14). The 5-yr progression-free survival rates were 88% (95% CI: 86-90%) vs. 89% (95% CI: 84-94%), respectively (HR 0.86, 95% CI 0.50-1.49). The 3-yr discontinuation-free survival rates were 51% (95% CI: 47-54%) vs. 51% (95% CI: 44-60%), respectively (HR 0.98, 95% CI 0.75-1.28).

ABU did not significantly affect BCG immunotherapy outcomes. Intravesical BCG during ABU is safe, with similar discontinuation rates, indicating very similar treatment tolerability.