A 53-year-old woman has noticed increasing malaise. On physical examination, there are no abnormal findings, but a stool guaiac test is positive. Her hemoglobin level is 7.9 g/dL. A colonoscopy is performed, and a 3-cm sessile mass is found in the cecum. A biopsy specimen of the mass shows a moderately differentiated adenocarcinoma confined to the mucosa. An abdominal CT scan shows no lymphadenopathy or hepatic lesions. Given this information, which of the following is the best course of action?

A malignant epithelial neoplasm arises in the mucosa but has a tendency to invade locally. A benign neoplasm is often well-circumscribed, and compressed normal surrounding tissue appears to form a discrete border. This localized lesion can be resected easily, with adequate margins. Without evidence for spread outside the colon, chemotherapy is unlikely to be of benefit. The biopsy specimen shows a malignant lesion; it must be removed before it increases in size and invades locally or metastasizes. If there is no family history, familial cancer with a high risk of recurrence from multiple polyps is unlikely; local excision is adequate. Such a solitary mucosal lesion is unlikely to represent a metastasis.