A 20-year comparison of definitive chemoradiation with 5-FU versus capecitabine in anal cancer patients treated at Stanford.

Abstract

710 Background: Capecitabine is an established treatment alternative to intravenous 5-fluorouracil (5-FU) for chemoradiation in rectal cancer. Few studies have compared the two agents in anal cancer. The objective of this retrospective study was to compare outcomes and toxicities in non-metastatic anal cancer patients undergoing definitive radiotherapy (RT) at Stanford combined with capecitabine/mitomycin (CM) versus 5-FU/mitomycin (FM). Methods: We included all non-metastatic anal cancer patients treated with definitive chemoradiation at Stanford from 1997 – 2016. Patients who received cisplatin or induction chemotherapy were excluded. Patient charts were reviewed and cause of death determined from the cancer registry. Fisher’s exact test was used to compare nominal parameters, Mann-Whitney U test for continuous variables. Gray’s test for equality was used to compare recurrence and colostomy incidence, and Log-rank test to compare disease-specific and overall survival. Results: Sixty-eight patients were treated at Stanford. Twenty-nine received FM and RT, 12 received standard 5-FU and 17 received low-dose continuous 5-FU; 39 patients received CM and RT. Median age was 59.5 years, and 56% were female. There was no difference in the 3-year overall and disease-specific survival between the FM and CM groups (81.5% v 90.5% p = 0.262; 88.1% v 96.0% p = 0.229). Incidence of recurrence was equivalent between the two groups (13.8% v 10.6%, p = 0.927) but patients in the combined FM group recurred earlier (6.9 v 20 months, p = 0.004) and distant recurrences were only seen in the CM group. Colostomy rates were higher in the FM group (14.6% v 2.8%, p = 0.082); all colostomies in the FM group were in patients receiving continuous 5-FU. Toxicities were similar between the two groups. The most common grade 2 or higher toxicities were dermatitis (77%), anal pain (77%), diarrhea (54%), stomatitis (19%), and nausea (22%). Conclusions: Overall and disease-specific survival and recurrence rates were equivalent between FM and CM groups. Recurrence patterns differed with loco-regional recurrences and higher colostomy rates in the FM group, while most recurrences in the CM group were distant.