Background: Morphologic, histochemical, and cytoproliferative characteristics differentiate hyperplastic polyps from adenomas. Even so, these polyps are indicators of populations with a high colorectal cancer risk. Since changes in mucosal cell proliferation are highly predictive biomarkers of the adenomacarcinoma sequence, this study examined the cytoproliferative profiles of mucosa bearing hyperplastic polyps, in a search for the significance of such lesions in bowel carcinogenesis.
Methods: Proliferative activity demonstrated by immunohistochemical detection of the in vitro uptake of bromodeoxyuridine was evaluated in the rectal mucosa of 26 patients with hyperplastic polyps, 35 with adenomas < 1 cm, 60 with adenomas > 1 cm, 10 with adenomas + synchronous hyperplastic polyps, and 400 controls.
Results: An upward shift of the major DNA synthesis zone to the intermediate and surface crypt compartments was found in all four patients groups. Significant hyperproliferation, on the other hand, was only observed in patients with large adenomas or hyperplastic polyps, or small adenomas and synchronous hyperplastic polyps.
Conclusions: These findings suggest that hyperplastic polyps are morphologic indicators of tumor initiation in the rectal mucosa and its ensuing hyperproliferation. Abnormalities in the distribution of proliferation in the mucosa do not appear to be specifically associated with the morphogenesis of hyperplastics polyps.