Urinary pH is an independent predictor of upper tract recurrence in non-muscle-invasive bladder cancer patients with a smoking history.

Limited information is currently available on predictors of upper tract urothelial carcinoma (UTUC) recurrence in non-muscle-invasive bladder cancer (NMIBC) patients according to smoking history, although smoking probably contributes to urothelial carcinogenesis. Therefore, the present study aimed to identify independent predictors of UTUC recurrence in all patients and those with a smoking history. Our study population comprised 1190 NMIBC patients who underwent transurethral resection of bladder tumor. UTUC developed in 43 patients during the follow-up. A history of bacillus Calmette-Guérin (BCG) therapy was independently associated with a lower incidence of UTUC (HR = 0.43; P = 0.011). In a subgroup of NMIBC patients with a smoking history, concomitant carcinoma in situ (CIS) and a lower urinary pH (< 6) were independently associated with a higher incidence of UTUC recurrence (HR = 3.34, P = 0.006 and HR = 3.73, P = 0.008, respectively). Among patients with a longer smoking duration (≥ 20 years) or larger smoking intensity (≥ 20 cigarettes per day), those with lower urinary pH (< 6) had a significantly higher UTUC recurrence rate than their counterparts. These results suggest that BCG instillation may prevent UTUC recurrence in NMIBC patients, while a lower urinary pH and concomitant CIS increase the risk of UTUC recurrence in those with a smoking history.