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 neoadjuvant 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 downstaged 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.