Toxicity, Tolerability, and Compliance of Concurrent Capecitabine or 5-Fluorouracil in Radical Management of Anal Cancer With Single-dose Mitomycin-C and Intensity Modulated Radiation Therapy: Evaluation of a National Cohort

Purpose: Chemoradiation therapy (CRT) with mitomycin C (MMC) and 5-fluorouracil (5-FU) is established as the standard of care for the radical treatment of patients with anal squamous cell carcinoma (ASCC). The use of the oral fluoropyrimidine-derivative capecitabine is emerging as an alternative to 5-FU despite limited evidence of its tolerability and toxicity.

Methods and Materials: A national cohort evaluation of ASCC management within the United Kingdom National Health Service was undertaken from February to July 2015. The toxicity rates were prospectively recorded. For the present analysis, we report data from ASCC patients who underwent intensity modulated RT and a single dose of MMC with either 5-FU (5-FU/MMC) or capecitabine (capecitabine/MMC). All were treated with radical intent and intensity modulated radiation therapy (IMRT) was delivered in accordance with UK guidance.

Results: Of the 242 patients received from 40 centers across the United Kingdom, 147 met the inclusion criteria; 52 of whom were treated with capecitabine/MMC and 95 with 5-FU/MMC. No treatment-related deaths and no overall difference were found in the proportion of patients experiencing any grade ≥3 toxicity between the capecitabine and 5-FU groups (45% vs 55%; P = .35). However, significantly fewer patients in the capecitabine/MMC group experienced grade 3 hematologic toxicity (4% vs 27%; P = .001). A lower proportion of patients completed their planned chemotherapy course in the capecitabine cohort, although this did not reach statistical significance (81% vs 90%; P = .21). The median RT duration was 38 days (interquartile range 38-39) for both groups. No difference was found in the 1-year oncologic outcomes.

Conclusions: Capecitabine/MMC resulted in similar levels of grade 3/4 toxicity overall compared with 5-FU/MMC as CRT for ASCC, although differences were found in the patterns of observed toxicities, with less hematologic toxicity with capecitabine. Further studies of capecitabine/MMC are required to understand the acute toxicity profile and long-term oncologic outcomes of this combination with intensity modulated RT for ASCC.