Urinary pH and the risk of recurrence in patients with non-muscle invasive bladder cancer.

Introduction: To evaluate the effect of urine pH on tumor recurrence rates in patients undergoing surveillance after initial diagnosis of non-muscle invasive bladder cancer (NMIBC).

Materials And Methods: All patients diagnosed with NMIBC at a tertiary referral center from January 2004 to March 2015 were reviewed. Our primary outcome was time to first recurrence after transurethral resection of bladder tumor (TURBT). Patients were analyzed according to the average urine pH of all urinalysis data over the surveillance period from TURBT to first recurrence. Kaplan-Meier survival analysis was used to determine differences in median time to recurrence. Cox proportional hazards regression was used to assess independent predictors of cancer recurrence.

Results: A total of 252 patients were included, of which 155 patients had average pH ≤ 6 (median pH 5.5) and 97 patients had average pH > 6 (median pH 6.8), p < 0.001. There was no significant difference in median time to recurrence between low/acidic pH (≤ 6) and high/basic pH (> 6) groups (28 months versus 17 months, respectively, p = 0.3444). Similarly, urine pH did not affect the risk of recurrence in a subgroup analysis stratified by smoking status. On multivariable Cox regression analysis, there was no association between average pH and recurrence among high grade tumors (HR = 1.33, 95% CI = 0.76 to 2.34, p = 0.3186), or low grade tumors (HR = 1.013, 95% CI = 1.01 to 1.58, p = 0.96).

Conclusions: There was no association between urine pH and risk of tumor recurrence, regardless of smoking status. These findings suggest that modification of urine pH is unlikely to decrease the frequency of tumor recurrence in patients with NMIBC.