Purpose: To compare the acute toxicities of concurrent chemoradiation (CCRT) with infusion 5-fluorouracil (5-FU) versus capecitabine in patients with locally advanced rectal cancer.

Materials and Methods: Between January 2015 and October 2015, 48 locally advanced rectal cancer patients from 7 radiotherapy centers in Thailand were randomized into 2 groups. The first group received infusion 5-FU chemotherapy (1,000 mg/m2 days 1-5 and 29-33) during the course of radiation treatment while the other group received oral capecitabine (825 mg/m2, twice daily, 5 days/week). The dose of whole pelvic radiation was 45-50.4 Gy. The acute toxicities during the course of treatment were recorded and compared.

Result: Forty-eight locally advanced rectal cancer patients were enrolled in the study, 21 patients were in 5-FU arm and 27 were in capecitabine arm. 47.9% were male and 52.1% were female with a median age of 59 years. Twenty- four patients were treated with preoperative CCRT and 24 patients with postoperative CCRT. No grade 3 or 4 dermatitis and genitourinary toxicities were observed. There were 83.3% of all patients developed diarrhea; 90.4% were in 5-FU arm and 77.8% were in capecitabine arm (p= 0.215). Two patients in 5-FU arm had grade 3 diarrhea but none in capecitabine arm. Grade 1 or 2 hand-foot syndrome developed in capecitabine arm more than 5-FU arm, 22.2% versus 9.6% (p= 0.359). The incidence of grade 1 or 2 anemia was 23.8% and 11.1% in 5-FU and capecitabine arm, respectively (p=0.463). No grade 3 or more anemia and thrombocytopenia were observed. Three patients in 5-FU arm had Grade 3 or 4 leucopenia (14.3%), all of these developed febrile neutropenia, whereas none was observed in capecitabine arm. No treatment related death occurred in this study.

Conclusion: This preliminary report showed that the acute toxicities of CCRT with capecitabine in locally advanced rectal cancer are comparable to the standard infusion 5-FU.