Peritoneal reflection involvement as a prognostic factor in rectal cancer. Long-term oncological outcomes from a prospective study.

Purpose: To assess the relevance of peritoneal reflection involvement in long-term oncological outcomes in patients with rectal cancer. Methods: prospective observational study from a specialized colorectal unit, that included a consecutive series of patients undergoing mesorectal excision for rectal cancer. PR involvement was evaluated on pathological examination using Shepherd’s classification. Overall survival (OS), disease-free survival (DFS) and local recurrence (LR) were assessed. Results: 160 patients were included in the present analysis. Peritoneal involvement was present in 28.2% of the 85 tumours above or at the level of PR. There were no differences in OS, DFS or LR according to tumour’s height location. The 5-year OS, DFS and LR for tumours involving PR were 58.3%, 61.7% and 30.3%, respectively. Patients with peritoneal involvement had a higher LR rate (p=0.02) and shorter OS (p=0.04). Shepherd’s grade 4 peritoneal involvement was an independent risk factor for OS (HR 2.9; 95% IC 1.1-9.5, p=0.04) and LR (HR 4.2; 95% IC 1.2-16.9, p=0.04). Conclusion: After rectal cancer resection, peritoneal involvement is an independent risk factor for local recurrence and poor survival.