Purpose: Aromatic amines, well-known bladder carcinogens, derived from cigarette smoke are activated by acidic urine. We herein determined whether urinary pH levels are associated with bladder recurrence in upper tract urothelial carcinoma patients with a positive smoking history. Methods: A total of 256 upper tract urothelial carcinoma patients who were surgically treated at our institution between 1990 and 2013 were included. Urinary pH levels were defined as the median of at least two consecutive measurements within 1 month of surgery. Results: Ninety-six patients (37.5 %) had pH <5.5 and 160 (62.5 %) had pH ≥5.5, and urinary pH levels were identified as one of the significant predictors for bladder recurrence in univariate but not multivariate Cox regression analysis in overall. In patients with a positive smoking history among those without a history of bladder tumor (N = 110), the 5-year bladder recurrence-free survival rate was 52.5 % in patients with pH ≥5.5, which was significantly higher than that in those with pH <5.5 (25.9 %, p = 0.032). In the multivariate analysis, urinary pH <5.5 (p = 0.022, HR; 1.86) was independently associated with bladder recurrence. No significant difference for bladder recurrence was observed between these two groups in patients with no smoking history among them. Conclusions: Urinary pH <5.5 is associated with an increased risk of bladder recurrence in upper tract urothelial carcinoma patients with a positive smoking history among those without a history of bladder tumor. Modifications to pH for urine alkalization may prevent bladder recurrence.
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