An immediate, single instillation of mitomycin C (MMC) after transurethral resection (TURBT) may reduce the risk of recurrence among patients with non-muscle-invasive bladder cancer (NMIBC) regardless of their prognostic risk group, according to a study published in Urologic Oncology.1
A prior meta-analysis suggested that an immediate instillation of chemotherapy post-operatively may not benefit all patients with NMIBC, leading to a European Association of Urology (EAU) guideline update recommending that patients with a prior recurrence rate greater than 1 per year and an EORTC recurrence score of 5 or greater no longer receive this intervention. Previous recommendations were based on an older study that no longer corresponded with new EAU risk groups; prompting a reevaluation using the same criteria.
For this retrospective study, researchers reclassified the original prospective cohort of 2243 patients with NMIBC to low-, intermediate-, or high-risk groups according to EAU definitions and calculated new EORTC scores to assess the treatment effect. In the previous study, patients were randomly assigned to receive a single, immediate (within 24 hours) or a single, delayed (2 weeks post-TURBT) instillation of MMC 40 mg; patients who were classified originally as intermediate- or high-risk received additional adjuvant instillations.
Based on the available data, 83% of patients were reclassified into EAU risk groups and 48% had new EORTC recurrence scores.
Results showed that 296 of 1048 patients who received immediate instillation compared with 407 of 1195 who received delayed instillation experienced disease recurrence. The time to recurrence (TTR) was significantly extended among patients who received immediate MMC (P < .001), which represented a 25% risk reduction compared with patients who received delayed instillation (hazard ratio, 0.75; 95% CI, 0.64-0.8; P < .001).
Patients who received immediate instillation did not have any significant differences in treatment effect, irrespective of being categorized as low-, intermediate-, or high-risk.
The authors concluded that “the treatment effect of an immediate instillation of MMC does not significantly differ between any of the subgroups. Based on these findings, patients should not a priori be withheld an immediate instillation of MMC after TURBT.”
- Bosschieter J, Nieuwenhuijzen JA, Vis AN, et al. An immediate, single intravesical instillation of mitomycin C is of benefit in patients with non-muscle-invasive bladder cancer irrespective of prognostic risk groups [published online July 28, 2018]. Urol Oncol. doi: 10.1016/j.urolonc.2018.05.026