When is endoscopic polypectomy adequate therapy for colonic polyps containing invasive carcinoma?

We correlated the histopathology with outcome for all patients with endoscopically removed colonic polyps containing invasive adenocarcinoma seen at our institution over a 10-yr period. Invasion was defined as infiltration of malignant cells into the submucosa. Of a total of 1523 adenomatous polyps, 41 polyps (2.7%) in 39 patients contained invasive adenocarcinoma. One patient was excluded from further analysis because of a synchronous colonic carcinoma. Fourteen patients (37%) had favorable histologic features (grade I or grade II carcinoma with free margin of resection and absence of lymphatic invasion), and none developed metastatic carcinoma during the follow-up period (mean 6.5 yr, range 4-10.6 yr). Twenty-four (63%) had unfavorable histologic features (grade III tumor with tumor at or near the margin of resection or lymphatic invasion), and 10 of these (42%) had either residual local or metastatic carcinoma in subsequent operations or during the follow-up period. This difference in outcome was statistically significant (p less than 0.05) when compared with the outcome of the group with favorable histology. We conclude that endoscopic polypectomy is adequate therapy for colonic polyps containing invasive carcinoma, provided that the favorable histologic features are present.