Influence of local peritoneal involvement on pelvic recurrence and prognosis in rectal cancer.

AIMS To evaluate the influence of involvement of the peritoneal surface by carcinoma of the rectum on local recurrence and prognosis. METHODS Prospective analysis of pathological prognostic factors in 209 resections for rectal carcinoma between 1988 and 1993 with meticulous pathological technique particularly to assess the relation of tumour to the peritoneal surface. Comprehensive clinical follow up with cause of death established from all available sources of information (hospital and general practitioner data) with necropsies where necessary. Local recurrence was determined by accepted clinical, radiological and pathological criteria. RESULTS Local peritoneal involvement was detected in 25.8% (54/209) of cases. It was more common in women and was associated with tumour differentiation, size and site, and lymph node involvement. Local peritoneal involvement showed considerable prognostic disadvantage in all cases and in curative cases alone. Multivariate analysis demonstrated independent prognostic disadvantage for all cases although this was lost in the curative group. With a 30 month median follow up time, comprehensive clinical surveillance detected 25 (12.0%) local recurrences. Thirteen (52%) palliative cases had shown spread to involve the mesorectal (deep, circumferential) resection margin. Of the 12 curative cases, six were upper rectal cancers with local peritoneal involvement suggesting that tumour seeding into the pelvic peritoneal cavity was the cause of local recurrence. Local recurrence of the six other rectal tumours was probably because of intraluminal seeding in two, involvement of the distal margin in one, extensive extramural venous involvement in two, and tumour spread to the bladder in one. CONCLUSIONS Comprehensive pathological analysis of a resection specimen can identify cases with a high probability of local recurrence which may benefit from early adjuvant therapy. Involvement of the peritoneal surface is a common event in rectal cancer, has adverse prognostic influence and may be an important factor in local recurrence of upper rectal carcinoma.