Relationship between urinary pH and efficacy of Bacillus Calmette-Guérin treatment in patients with carcinoma in situ of the bladder.

Purpose: Bacillus Calmette-Guérin (BCG) is the standard treatment for carcinoma in situ (CIS) in patients with urothelial bladder carcinoma. We aimed to determine whether average urinary pH before BCG instillation affects the BCG response.

Methods: Between August 2003 and January 2023, 203 patients with CIS received BCG treatment (Tokyo strain, 80 mg, ≥ 5 times) at our hospital. Average urinary pH was calculated by summing each urinary pH measurement before BCG instillation and dividing by the number of instillations. The Fine-Gray method was used to assess the relationship between average urinary pH (as a continuous variable) and intravesical recurrence. We also analyzed the cumulative incidence of intravesical recurrence after BCG treatment using different cutoff values for average urinary pH (median and trisection of the cohort).

Results: The median follow-up period was 45 months (interquartile range (IQR): 14-83 months). The median urinary pH was 6.07 (IQR: 5.68‒6.50). In multivariate analysis, average urinary pH before BCG was significantly associated with intravesical recurrence (hazard ratio: 0.53, 95% confidence interval 0.32-0.89, p = 0.017). The cumulative incidence of intravesical recurrence differed significantly when categorized by average urinary pH (median and trisection), with patients having higher urinary pH showing lower intravesical recurrence rates.

Conclusion: This is the first study to examine the relationship between BCG response and average urinary pH in patients with CIS. Patients with higher urinary pH had lower intravesical recurrence rates after BCG treatment.