One compared with two cycles of mitomycin C in chemoradiotherapy for anal cancer: analysis of outcomes and toxicity

Background Concurrent chemoradiation with fluorouracil (5(FU)) and mitomycin C (MMC) is standard treatment for anal canal carcinoma (ACC). The current protocol in Alberta is administration of 5(FU) and MMC during weeks 1 and 5 of radiation. However, administration of the second bolus of MMC has been based largely on centre preference. Given limited published data on outcomes with different MMC regimens, our objective was to compare the efficacy and toxicity of 1 compared with 2 cycles of MMC in ACC treatment. Methods Our retrospective study evaluated 169 ACC patients treated with radical chemoradiotherapy between 2000 and 2010 at two tertiary cancer centres. All patients were treated with 2 cycles of 5(FU) and with 1 cycle (MMC1) or 2 cycles (MMC2) of MMC. Acute toxicities, disease-free (DFS) and overall survival (os) were analyzed. Results Baseline demographics, performance status, and stage were similar in the groups of patients who received MMC1 (52%) and MMC2 (48%). Before treatment, median hematologic parameters were comparable, except for white blood cell count, which was higher in the MMC2 group, but within normal range. The 5-year os and DFS were similar (75.1% and 54.2% for MMC1 vs. 70.7% and 44.2% for MMC2, p = 0.98 and p = 0.63 respectively). On multivariate analysis, MMC2 was the factor most strongly associated with specific acute toxicities: grade 3+ leukopenia (hazard ratio: 4.82; p < 0.01), grade 3+ skin toxicity (hazard ratio: 4.76; p < 0.001), and hospitalizations secondary to febrile neutropenia (hazard ratio: 9.91; p = 0.001). Conclusions In definitive chemoradiotherapy for ACC, 1 cycle of MMC appears to offer outcomes similar to those achieved with 2 cycles, with significantly less acute toxicity.