Long-term prognosis of well-differentiated adenocarcinoma in endoscopically removed colorectal adenomas.

Thirty-six malignant polyps were identified that met the following criteria: well-differentiated adenocarcinoma and complete excision endoscopically. Location, type, size, distance of the cancer to the cautery mark, and lymphovascular involvement were analyzed to determine if they affected findings at surgery or risk of recurrent cancer. There were 20 patients and 21 polyps in the nonsurgical group, and 15 patients and polyps in the surgical group. One patient from each group had residual cancer after endoscopic removal of the polyp. The only factor that had an adverse effect on outcome was the distance of the cancer to the cautery mark (< 1 mm). Although rectal location was associated with the residual cancer, poor prognosis could have been predicted by the inadequate margins. This long-term follow-up (65 months average) study supports previous observations that an adequate margin is the most important factor in predicting the prognosis of endoscopically resected colorectal adenomas containing well-differentiated adenocarcinomas.