Mitomycin C vs. Bacillus Calmette-Guerin for treatment of intermediate-risk nonmuscle invasive bladder cancer patients-A comparative analysis from a single center

Background: Induction followed by 1 year maintenance instillation of intravesical Bacillus Calmette-Guerin (BCG) is the standard treatment for intermediate-risk (IR) nonmuscle invasive bladder cancer (NMIBC) patients. Few data exist on the efficacy of Mitomycin C (MMC) instillation in this setting.

Methods: We retrospectively analyzed 226 IR-NMIBC patients classified by the International Bladder Cancer Group (IBCG) and 250 IR-NMIBC intravescical treatment-naïve patients classified by the European Association of Urology (EAU). All patients received either a full induction course of BCG or 40 mg/40 ml MMC from 2012 to 2022. Optimal treatment was defined as 1-year maintenance for BCG and 11 monthly maintenance instillations for MMC. Kaplan-Meier analysis estimated recurrence-free survival (RFS) before and after inverse probability of treatment-weighting (IPTW) and progression-free survival (PFS). Multivariable Cox regression was used to evaluate difference in recurrence after adjustment for clinically relevant variables before and after IPTW.

Results: Optimal BCG and MMC courses were administered to 21% of IR-IBCG and 23% of IR-EAU patients. At 4-years, patients treated with optimal MMC and BCG treatment had similar RFS and PFS in both EAU and IBCG groups. Patients receiving nonoptimal BCG compared to optimal MMC exhibited lower 4-year RFS after IPTW (82% vs. 68% in EAU and 82% vs. 65% in IBCG). At 4-year optimal MMC had greater PFS non optimal BCG. Optimal MMC treatment predicted recurrence in EAU (adjusted and weighted HR 0.33, 95% CI, 0.11-0.98) and IBCG (adjusted and weighted HR 0.29, 95% CI, 0.08-0.97) groups compared to nonoptimal BCG.

Conclusions: Optimal 40 mg/40 ml MMC treatment was as effective as optimal BCG in IR-IBCG and IR-EAU NMIBC patients, reducing both recurrence and progression compared to nonoptimal BCG. MMC could be a valid first line alternative to BCG for both IR-EAU and IR-IBCG intravescical treatment-naïve patients, during BCG shortages.