Routine short course pre-op radiotherapy or selective post-op chemoradiotherapy for resectable rectal cancer? Preliminary results of the MRC CR07 randomised trial

Abstract

3511 Background: Radiotherapy reduces local recurrence (LR) when combined with surgery in resectable rectal cancer. The Medical Research Council CR07 trial was designed to compare two different radiotherapy policies when combined with mesorectal excision. Methods: Patients with operable non-metastatic adenocarcinoma of the rectum were randomised to either routine pre-op short course radiotherapy [25Gy/5F] (PRE) or selective post-op chemoradiotherapy (POST) for patients with involvement of the circumferential resection margin (CRM) - [45Gy/25F + 5fluorouracil]. Results: A total of 1350 patients were randomised from 52 centres in the UK, Canada, New Zealand and South Africa between March 1998 and August 2005. Median follow-up is 3 years. Patients (73% male, median age 65 years, 79% PS0) were well balanced between the 2 arms. 595 of 674 (88%) of the pre-op group received their allocated treatment. Of the 676 patients allocated to the selective post-op chemoradiotherapy arm, 73 (11%) were CRM +ve and 51 of these (70%) received chemoradiotherapy. Post operative chemotherapy was received by 85% of patients with stage III disease. At the time of analysis 23 PRE and 61 POST patients had confirmed LR, 96 and 106 patients respectively distant metastases, and 115 and 146 respectively had died. The 3 year rates for LR (primary end point) were 4.7% and 11.1% for PRE and POST groups respectively (HR 2.47, 95% CI 1.61–3.79), for disease free survival 79.5% and 74.9% (HR 1.31, 95% CI 1.02–1.67) and for overall survival 80.8% and 78.7% (HR 1.25, 95% CI 0.98–1.59. The LR benefit in favour of PRE was consistent for tumours 0–5,5–10 and >10cm from the anal verge (HR 2.00, 2.14 and 4.97 respectively). Further subset analysis based on TNM stage and operation performed will be presented. Conclusions: These preliminary results indicate that routine short course pre-operative radiotherapy results in a signifcant reduction in local recurrence and improved disease free survival at 3 years when compared with a highly selective post operative approach. No significant financial relationships to disclose.