The prognostic importance of peritoneal involvement in colonic cancer: A prospective evaluation

Background & Aims: prognostic parameters specific to the colon have been somewhat neglected compared with the rectum. This study was instituted to assess the influence of local peritoneal involvement (LPI) on pelvic and intraperitoneal recurrence and prognosis in an unselected, prospective series of colonic cancer resections. Methods: Meticulous examination of 412 resections included evaluation of the relation of the tumor to the peritoneal surface. Histological assessment was as follows: 1, peritoneal involvement absent (81 resections, 20%); 2, inflammatory reaction with tumor close but not present at the surface (89 resections, 22%); 3, peritoneal surface unequivocally infiltrated (112 resections, 27%); and 4, peritoneal involvement with ulceration and tumor cells lying apparently free in the peritoneum (130 resections, 32%). Results: LPI showed strong independent prognostic influence in both curative surgery groups and in all patients. In multivariate analysis in curative surgery, LPI was the most powerful prognostic indicator. It was significantly associated with palliative surgery, extent of local spread, and mucinous subtype and predicted cases with subsequent intraperitoneal recurrence and/or persistence. Conclusions: LPI is a common event in colonic cancer and is a consistent predictor of subsequent intraperitoneal recurrence. It is an important independent pathological prognostic parameter and may supersede other parameters in current usage in colonic cancer prognosis.