Rodrigo Perez, Angelita Habr-Gama, Ulysses Ribeiro Jr., Afonso Sousa Jr., Fabio G. Campos, Wladimir Nadalin, Victor Seid, Arazawa Sidney, University of Sao Paulo Medical School, Sao Paulo, Brazil

Introduction: Neoadjuvant chemoradiation treatment has resulted in significant tumor down-staging and improved local disease control for distal rectal cancer. Overall survival and disease-free survival may be associated with final pathological stage 0-III and complete clinical response. Patients and Methods: 260 patients with distal (0-7cm from AV) rectal adenocarcinoma considered resectable were treated by neoadjuvant chemoradiation with 5-FU and Leucovorin plus 5040 cGy. Patients with incomplete clinical response were treated by radical surgical resection. Patients with complete clinical response were treated by non-operative treatment and were followed by an experienced colorectal surgeon. Patients with complete clinical response were considered stage c0 and patients with complete pathological response were considered stage p0. Statistical analysis was performed using Chi-squared, student T test and Kaplan-Meier curves. Results: 71 patients (28%) showed complete clinical response (Stage c0). 22 patients (9%) showed incomplete clinical response, were operated on and pathological examination revealed pT0N0M0 (Stage p0).59 patients (22%) had stage I, 68 (26%)had stage II and 40 patients (15%) had stage III disease. Overall survival rates were significantly higher in stage c0 (p=0.01) compared to stage p0. Disease-free survival rate showed a trend towards better results in stage c0.Ten-year overall survival rates for stage p0 and c0 were 84% and 93% respectively. Five-year overall and disease-free survival rates were 97.7% and 84% (stage 0); 94% and 74% (stage I); 77% and 50% (stage II); and 50% and 28% (stage III). Conclusions: Neoadjuvant chemoradiation therapy may result in significant tumor downstaging in patients with distal rectal cancer. Stage 0 disease is associated with excellent long-term results irrespective of treatment strategy. Surgical resection may not lead to improved outcome in this situation (stage 0 disease)and result in significant rates of unnecessary stomas. Furthermore, survival may be directly correlated to final pathological staging.