The most appropriate management is to repeat colonoscopy in 3 months. A malignant polyp was discovered during this patient's colonoscopy and was endoscopically resected. Invasive adenocarcinoma arising in a pedunculated polyp may be considered adequately treated by endoscopic en bloc polypectomy alone if the lesion is confined to the submucosa and possesses no adverse histologic features such as poor differentiation, lymphatic or vascular invasion, or involved margins. National recommendations for postpolypectomy surveillance intervals are as short as 3 to 6 months in patients with large (>2 cm) adenomas or adenomas with invasive cancer and favorable prognostic features. These shorter surveillance intervals help to ensure that no residual polyp tissue remains.
If any adverse histologic features are noted, the risk of lymph node involvement is increased substantially and surgical resection of the involved colon is required. Surgical resection should also be considered if the lesion is removed piecemeal and the adequacy of resection cannot be confirmed.
Since this tumor is endoscopically cured, neither radiation therapy nor CT scan of the abdomen or pelvis is necessary.