Intravesical mitomycin C (MMC) and MMC + cytosine arabinoside for non‐muscle‐invasive bladder cancer: a randomised clinical trial

To compare the urinary pH, recurrence-free survival (RFS), and safety of adjuvant intravesical therapy in patients with non-muscle-invasive bladder cancer (NMIBC) receiving mitomycin C (MMC) therapy and MMC + cytosine arabinoside (Ara-C) therapy.A total of 165 patients with NMIBC from six hospitals were randomly allocated to two groups: weekly instillation of MMC + Ara-C (30 mg/30 mL + 200 mg/10 mL) for 6 weeks and the same instillation schedule of MMC (30 mg/40 mL). The primary outcome was RFS, and secondary outcomes were urinary pH and toxicity in the two groups.A total of 81 and 87 patients were randomised into the MMC and MMC + Ara-C groups, respectively. Overall, the RFS in the MMC + Ara-C group was significantly longer (P = 0.018) than that in the MMC group. A similar significant difference was detected in patients with intermediate-risk NMIBC, but not in those with high-risk NMIBC. The mean (SD) urinary pH was significantly higher in the MMC + Ara-C group than in the MMC group, at 6.56 (0.61) vs 5.78 (0.64) (P < 0.001), and the frequency of a urinary pH of >7.0 in the MMC and MMC + Ara-C groups was 6.3% and 26.7%, respectively (P < 0.001). Multivariate analysis models including clinicopathological features and second transurethral resection demonstrated that increased urinary pH was associated with better outcomes (hazard ratio 0.18, 95% confidential interval 0.18-0.038; P < 0.001). In all, there were 14 and 10 adverse events in the MMC and MMC + Ara-C groups, respectively, without a significant difference (P = 0.113).Our randomised clinical trial suggested that intravesical therapy with MMC and Ara-C is useful and safe for patients with intermediate-risk NMIBC. Increase in urinary pH with Ara-C is speculated as a mechanism for increased anti-cancer effects.