Outcomes of clinical T4M0 extra-peritoneal rectal cancer treated with preoperative radiochemotherapy and surgery: a prospective evaluation of a single institutional experience.

Background: Our objective was evaluate the outcome of primary clinical T4M0 extraperitoneal rectal cancer treated by neoadjuvant radiochemotherapy. Prognosis of clinical T4 rectal cancer is poor. Preoperative chemoradiation therapy may be beneficial. The results obtained are unclear due to lack of objective and strictly applied staging methods.

Methods: Patients with primary, clinical, T4MO, extraperitoneal rectal cancer, defined by transrectal ultrasonography, computed tomography or magnetic resonance imaging, were considered. Intraoperative radiotherapy and adjuvant chemotherapy were employed in some patients after curative resection (R0). Variables influencing the possibility to perform an R0 resection and a sphincter-saving procedure were investigated as predictors of outcome.

Results: 100 patients were included. R0 resection was performed in 78 patients. R0 resection rate was greater in females (93% vs 67%) and in responders to neoadjuvant chemoradiation (94% vs 60%). The ability to perform a sphincter-saving procedure was 57%, greater in middle rectal location (85% vs 51%) and in responders to the chemoradiation (70% vs 47%). Median follow-up was 31 months (range, 4-136). Local recurrences were found in 7 patients (10%). Five-year local control in R0 patients was 90% and better in the IORT group (100%). Distant relapse occurred in 24 patients (30%). Five-year overall survival was 59%, and was better after an R0 versus an R1 or R2 resection (68% vs 22%). Overall and disease free survival in R0 patients improved after overall downstaging. Adjuvant chemotherapy given in addition to the neoadjuvant therapy did not appear to offer benefit in improving survival.

Conclusion: A multimodal approach enabled us to obtain a 5-year overall survival of about 60%. IORT increased local control. The role of adjuvant chemotherapy needs to be further investigated.