How important is peritoneal involvement in rectal cancer? A prospective study of 331 cases

Background and aims: The importance of circumferential resection margin involvement in predicting locoregional recurrence and death from rectal cancer is well known. However, it is well accepted that cases of rectal carcinoma recur when this surgical margin is not compromised. The aim of this study was to analyse the influence of peritoneal involvement, among other clinicopathological variables, on locoregional recurrence and overall prognosis in an unselected prospective series of rectal cancer resections. Methods and results: This unselected prospective study assessed 331 rectal carcinoma cases from a colorectal cancer study that recruited more than 1000 cases. Meticulous pathological examination was performed by one pathologist, with particular attention paid to the peritoneal surface. All clinicopathological variables were entered into a database with comprehensive clinical follow-up. Peritoneal involvement was a significant factor in prognosis on univariate analysis but not on multivariate analysis. However, in analysing the causes of locoregional recurrence specifically, it may have been a factor in causing this in up to half the cases. Conclusions: This study adds to the small amount of literature data on the potential importance of peritoneal involvement in predicting locoregional recurrence and overall prognosis, especially in upper rectal cancer.