Epithelial cell kinetics in the remaining colorectal mucosa after surgery for cancer of the large bowel.

We used microautoradiography in order to evaluate cell replication of the remaining colorectal mucosa in 20 patients previously operated on for cancer of the large bowel. The results were compared to those of 24 controls without neoplasms or other relevant colorectal disease. Samples of colorectal mucosa were taken during endoscopy. At histological examination each labeled intestinal hemicrypt was divided into 5 longitudinal compartments, from the base to the surface, and S-phase cells in each compartment were counted. Total labeling index (LI, ratio of labeled to total cells x 100) and labeling index per crypt compartment were similar in surgical patients and in controls. In contrast, both total LI and labeling index in the upper portions of the crypt (compartments 3, 4, and 5) were significantly higher in the 9 patients who showed recurrence of polyps than in those (n = 11) without recurrence. The LI in compartments 4 and 5 (the "high crypt region") was 4.37 +/- 0.95 (SEM) in patients with recurrence versus 0.88 +/- 0.21 (P less than 0.001) in patients with negative endoscopy finding and 1.47 +/- 0.22 in controls. Moreover, the fifth compartment was labeled in 8 of 9 individuals in whom polyps recurred but in only 2 of 11 patients without recurrence and 3 of 24 controls. In conclusion, after resection for large bowel cancer colonic epithelial cell proliferation tends to become more quiescent and similar to that of controls. However, in the subgroup of patients in whom polyps reappear, the colorectal mucosa maintains a hyperproliferative state with an expansion of the replicative zone to the most superficial portions of the crypt. These findings support the sequence adenoma-carcinoma and suggest that the evaluation of cell proliferation might be useful in the identification of subjects at increased risk for multiple tumors of the large bowel.