Interim analysis of the Stockholm III trial of preoperative radiotherapy regimens for rectal cancer

Background To address issues regarding the fractionation of radiotherapy (RT) and timing of surgery for rectal cancer, a multicentre trial has randomized patients to preoperative short-course RT with two different intervals to surgery, or long-course RT with delayed surgery. The present interim analysis assessed feasibility, compliance and complications after RT and surgery. Methods Some 303 patients were randomized to either short-course RT (5 × 5 Gy) and surgery within 1 week (group 1), short-course RT and surgery after 4–8 weeks (group 2) or long-course RT (25 × 2 Gy) and surgery after 4–8 weeks (group 3). Results Demographic data were similar between groups and there were few protocol violations (5·0–6 per cent). Eight patients (2·6 per cent) developed radiation-induced acute toxicity. There were no significant differences in postoperative complications between groups (46·6, 40·0 and 32 per cent in groups 1, 2 and 3 respectively; P = 0·164). Patients receiving short-course RT with surgery 11–17 days after the start of RT had the highest complication rate (24 of 37). Conclusion Compliance was acceptable and severe acute toxicity was low, irrespective of fractionation. Short-course RT with immediate surgery had a tendency towards more postoperative complications, but only if surgery was delayed beyond 10 days after the start of RT. Registration number: NCT00904813 (http://www.clinicaltrials.gov).