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?