Pathologic risk factors of occult malignancy in endoscopically unresectable colonic adenomas

With the advent of new endoscopic and laparoscopic techniques, the likelihood of colonoscopically unresectable adenomas harboring occult malignancy influences management. While prior studies have evaluated polyp size and morphology in assessing the risk of malignancy, the relative risk of cancer based on the presence or absence of high-grade dysplasia has not been systematically studied.

For all lesions preoperatively diagnosed as adenomas without invasive cancer, multivariate logistic regression analysis was performed to elicit independent variables associated with malignancy in the resected specimen.

One hundred patients underwent a colectomy for preoperatively diagnosed adenomatous lesions. Multivariate logistic regression analysis revealed size, degree of dysplasia, and left-sided location to be independent predictors of malignancy.

In colonic adenomas which are not amenable to simple colonoscopic resection, the most useful predictors of the lesion harboring a malignancy are polyp size and the presence of high-grade dysplasia, and these factors can help determine management.