Capecitabine With Mitomycin Reduces Acute Hematologic Toxicity and Treatment Delays in Patients Undergoing Definitive Chemoradiation Using Intensity Modulated Radiation Therapy for Anal Cancer

Purpose To assess the impact on acute toxicity of replacing 5-fluorouracil (5-FU) with capecitabine in definitive chemoradiation for patients with anal squamous cell carcinoma (ASCC). Methods and Materials We retrospectively reviewed the records of 107 consecutive patients with nonmetastatic ASCC treated with definitive chemoradiation from January 2009 to May 2014. In 2011, based on the noninferiority of capecitabine versus 5-FU, our institutional practice shifted to use capecitabine instead of 5-FU for ASCC. Of 107 patients, 63 were treated with infusional 5-FU (1000 mg/m²/day for 4 days) and mitomycin C (MMC) (10 mg/m²) during weeks 1 and 5, and 44 patients were treated with capecitabine (825 mg/m² twice daily) Monday through Friday throughout radiation therapy (RT) and MMC (10 mg/m²) during weeks 1 and 5. The incidence of grade 3 to 4 acute toxicity was compared between the 2 groups. Results The median age at diagnosis was 59 years, and 78 patients (73%) were female. The patient characteristics were similar between the 2 treatment groups. All patients in both groups were treated with intensity modulated RT (median dose, 56 Gy). In the 5-FU group, 52% experienced grade 3 to 4 neutropenia compared with 20% in the capecitabine group (P=.001). Treatment breaks resulting from toxicity, primarily related to grade 3+ hematologic toxicity, were necessary for 42% of patients treated with 5-FU versus 16% of those treated with capecitabine (P=.006). Conclusions Pelvic radiation therapy with MMC plus capecitabine was well tolerated and appeared to have less grade 3+ acute hematologic toxicity and fewer treatment interruptions than in a population of ASCC patients undergoing definitive chemoradiation with MMC and 5-FU.