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/m/day for 4 days) and mitomycin C (MMC) (10 mg/m) during weeks 1 and 5, and 44 patients were treated with capecitabine (825 mg/m twice daily) Monday through Friday throughout radiation therapy (RT) and MMC (10 mg/m) 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.