P-166 Operative versus nonoperative treatment for stage 0 rectal cancer following chemoradiation therapy

Abstract

In locally advanced rectal cancer, preoperative chemoradiotherapy (pCRT) is the standard care, aiming at downstaging and downsizing the tumor prior to potential radical surgery (1, 2). However, response to pCRT is highly variable, with only 8-20% of the patients exhibiting a complete pathological response (3). Surgical resection of the rectum may be associated with significant morbidity and mortality. Moreover, surgical resection may not lead to increased overall and disease-free survival in these patients. For this reason, we aimed to compare 2 groups of patients submitted to pCRT: one group without total clinical response therefore needing surgery (ypT0), and another with total clinical response, that did not need surgery (ycT0). Forty-six patients with rectal adenocarcinoma considered resectable were treated by pCRT. Complete and incomplete clinical responses were defined based on pelvic resonance magnetic, thoracic and abdominal tomography and endoscopic findings. Patients with incomplete clinical response were submitted to surgery resulting in stage ypT0. This group was compared to patients with complete clinical response with pCRT alone (ycT0) The statistical analysis was performed with Statistical Package for Social Sciences, version 26 (SPSS Inc., Chicago, IL, USA). Statistical analysis was performed using X2, Mann-Whitney U test and Kaplan-Meier curves. Three-year disease-free survival rate was 92.5%. In 13 patients (28.3%) complete clinical response was observed following pCRT (Non-surgical group). Thirty-three patients (71.7%) showed incomplete clinical response and were submitted to surgery. Anatomopathological results revealed ypT0N0M0 (Surgical group). Mean time until surgery was 10.7 weeks. There were no differences in patient demographics or tumor characteristics between groups. In the Surgical group, 18 definitive colostomies and 7 diverting temporary ileostomies were performed. Mean follow-up was 45.1 months in the Non-surgical group and 37.5 months in the Surgical group. There were 3 systemic recurrences and 1 endorectal recurrence in the Surgical group, with no recurrences in the Non-surgical group. Three patients in the Surgical group died of the disease. Two-year disease-free survival rates were 89.3% in the Surgical group and 100% in the Non-surgical group. Stage 0 rectal cancer disease is associated with excellent long-term results regardless of treatment strategy.