RISK FACTOR ASSESSMENT OF ENDOSCOPICALLY REMOVED MALIGNANT COLORECTALPOLYPS

Background-Malignant colorectal polyps are defined as endoscopically r emoved polyps with cancerous tissue which has invaded the submucosa. V arious histological criteria exist for managing these patients. Aims-T o determine the significance of histological findings of patients with malignant polyps. Methods-Five pathologists reviewed the specimens of 85 patients initially diagnosed with malignant polyps. High risk mali gnant polyps were defined as having one of the following: incomplete p olypectomy, a margin not clearly cancer-free, lymphatic or venous inva sion, or grade III carcinoma. Adverse outcome was defined as residual cancer in a resection specimen and local or metastatic recurrence in t he follow up period (mean 67 months). Results-Malignant polyps were co nfirmed in 70 cases. In the 32 low risk malignant polyps, no adverse o utcomes occurred; 16 (42%) of the 38 patients with high risk polyps ha d adverse outcomes (p<0.001). Independent adverse risk factors were in complete polypectomy and a resected margin not clearly cancer-free; al l other risk factors were only associated with adverse outcome when in combination. Conclusion-As no patients with low risk malignant polyps had adverse outcomes, polypectomy alone seems sufficient for these ca ses. In the high risk group, surgery is recommended when either of the two independent risk factors, incomplete polypectomy or a resection m argin not clearly cancer-free, is present or if there is a combination of other risk factors. As lymphatic or venous invasion or grade III c ancer did not have an adverse outcome when the sole risk factor, opera tions in such cases should be individually assessed on the basis of su rgical risk.