PROLIFERATIVE PATTERNS OF RECTAL MUCOSA AS PREDICTORS OF ADVANCED COLONIC NEOPLASMS IN ROUTINELY PROCESSED RECTAL BIOPSIES

Objectives: We sought to determine whether the evaluation of rectal ce ll proliferation in routinely processed rectal biopsies of apparently normal mucosa can predict the presence of advanced colonic neoplasms. Methods: Fifty consecutive patients, who did not meet any of the follo wing exclusion criteria, underwent total colonoscopy. Patients with no nadvanced adenomas, inflammatory bowel disease, hereditary predisposit ion to colonic cancer, or a history of colonic neoplasms were excluded . Patients with neoplasms in the distal 40 cm of the large bowel were also excluded. An adenoma was considered advanced if it had a diameter > 1 cm, or villous or severe dysplasia histology were present. In 26 of the 50 patients (Group A: 16 men, 10 women; mean age, 65 yr) advanc ed colonic neoplasms (advanced adenomas or cancer) were detected; in t he remaining 24 (Group B: 13 men, 11 women; mean age, 66 yr) the large bowel was free of neoplasms. In all patients the proliferative patter ns of apparently normal rectal mucosa were evaluated using the monoclo nal antibody MIB-1 to assess the expression of Ki-67 antigen in routin ely processed tissues. Proliferation index for the entire crypt, as we ll as proliferation indices for each of the five equal compartments, i nto which the crypt had been divided longtudinally, were calculated fo r each patient. Results: The mean proliferation indices were similar b etween the two groups compared. The mean proliferation index for the u pper crypt compartments (4 + 5) in the Group A patients was significan tly higher than for those of the Group B patients (p < 0.01). Multivar iate stepwise logistic regression analysis revealed that among gender, age, and proliferative parameters, the pattern of cell proliferation in the upper rectal crypt (4 + 5) compartment was the only predictor o f advanced colonic neoplasms (beta = 11.01, p < 0.001). Conclusions: O ur data suggest that the evaluation of the upward expansion of the rec tal crypt proliferative zone in routinely processed rectal biopsies of apparently normal mucosa appears to predict the presence of advanced colonic neoplasms. These preliminary results should be confirmed in la rger studies. (Am J Gastroenterol 1998;93:1472-1477. (C) 1998 by Am. C ell. of Gastroenterology).