A comparison of overall and disease-specific survivals following adjuvant radiotherapy with neo-adjuvant radiotherapy for rectal cancer

Abstract

e15008 Background: Preoperative radiotherapy is the preferred treatment for stage II-III rectal cancer. This arose following publication of the results of the German Rectal Cancer Study Group. It demonstrated a statistically significantly reduced local recurrence rate, and reduced toxicity for preoperative treatment compared with postoperative treatment. However, it failed to demonstrate improved overall survival. This study used the Surveillance, Epidemiology, and End Results (SEER) Program to compare overall and disease specific survival in rectal cancer patients treated with preoperative versus those receiving postoperative radiotherapy. Methods: 14,553 patients were identified with stage II-III rectal cancer, treated with either preoperative (5,136 patients) or postoperative radiotherapy (9,417 patients). Kaplan-Meier survival analyses and Cox multivariate analyses were used to compare 5 and 10 year overall and disease specific survival rates. Cause of death (COD) recorded as ‘Rectum and Rectosigmoid Junction’ was used to calculate rectal-specific survival. CODs recorded as ‘Colon excluding Rectum’ and ‘Rectum and Rectosigmoid Junction’ were used for colorectal-specific survival. Results: Kaplan-Meier analysis failed to demonstrate any statistical significant differences in survival figures. Cox multivariate analysis returned hazard ratios for overall survival of 1.207 (95% CI 1.122 - 1.298) and 1.180 (95% CI 1.103 - 1.263) at 5 and 10 years respectively for preoperative radiotherapy when compared with postoperative radiotherapy. For rectal-specific survival, 5 and 10 year hazard ratios of 1.381 (95% CI 1.239 - 1.539) and 1.342 (95% CI 1.210 - 1.489) respectively were obtained. Colorectal-specific survival returned 5 and 10 year hazard ratios of 1.222 (95% CI 1.124 - 1.329) and 1.193 (95% CI 1.101–1.292) respectively. Conclusions: Preoperative radiotherapy is the preferred treatment for stages II-III rectal cancer. This is because of its decreased risk of local recurrence and more optimal toxicity profile. However, this study suggests that preoperative radiotherapy is associated with poorer survival when compared with postoperative radiotherapy in the treatment of stage II-III rectal cancer. No significant financial relationships to disclose.