Mitomycin C (MMC) instillation within 24 hours after transurethral resection (TURBT) of non-muscle invasive bladder cancer (NMIBC) significantly reduces the risk of recurrence and delays the time to recurrence.
According to a prospective multicenter randomized phase III trial conducted in the Netherlands, this benefit was noted even in those patients who subsequently received adjuvant MMC based on risk category. The findings were published online in European Urology (July 10, 2017).
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In this report by Bosschieter et al, patients were preoperatively randomized to receive 40 mg MMC in 50 mL saline, either immediately (within 24 hours after TURBT) or in a delayed fashion (2 weeks after TURBT). The efficacy endpoints were defined as recurrence risk, time to recurrence, and progression risk, while safety endpoints measured were incidence and severity of adverse effects.
Of the 2,844 patients, 1,384 (49%) were assigned to an immediate instillation and 1,460 (51%) to a delayed instillation group. A total of 601 patients were excluded due to not meeting the study criteria, thus leaving 2,243 patients eligible for intention-to-treat analysis. After TURBT, patients were categorized as low risk (LR): primary, solitary pTa/pT1 grade 1–2 tumor; intermediate risk (IR): primary, solitary pTa/pT1 grade 3 tumor or recurrent, solitary pTa/pT1 grade 1–3 tumor; or high risk (HR): all multiple tumors and/or carcinoma in situ, independent of stage or grade. The LR group received no further adjuvant MMC, the IR group received three weekly and five monthly instillations, and the HR group received three weekly and 11 monthly instillations. Cystoscopy was performed every 3 months for 1 year and then every 6 months.