Improvement of survival with response to neoadjuvant radiation therapy for rectal cancer

Objectives: To determine whether patients with a complete or near-complete response to neoadjuvant radiation therapy (XRT) have improved survival compared with those with less of a response and to compare survival between patients with disease downstaged after neoadjuvant XRT and patients with stage I disease undergoing resection alone. Design, Setting, and Patients: Retrospective cohort of 10 971 patients (3760 patients with neoadjuvant XRT; 7211 with stage I disease with resection alone) from the Surveillance, Epidemiology, and End Results registry using data from January 1, 1994, through December 31, 2003. Main Outcome Measures: Overall survival and disease-specific survival (DSS) of patients undergoing resection for nonmetastatic rectal adenocarcinoma receiving neo-adjuvant XRT and patients with stage I disease undergoing surgical resection alone. Results: The 5-year DSS and overall survival were 94% and 82%, respectively, for responders to neoadjuvant XRT, 78% and 60%, respectively, for nonresponders, and 97% and 79%, respectively, for patients with stage I disease undergoing resection alone. Responders had improved DSS (P <.001) and overall survival (P<.001) compared with nonresponders by Cox regression. Patients with stage I disease undergoing resection alone had improved DSS (P=.01) but not overall survival (P=.89) compared with XRT responders. Conclusions: Patients with rectal adenocarcinoma down-staged after neoadjuvant XRT have improved survival compared with nonresponders. While DSS is excellent for responders to neoadjuvant XRT, it did not equal the DSS of patients with stage I disease undergoing resection alone.