A 65-year-old healthy man underwent colonoscopy for constipation. An endoscopically traversable mid-sigmoidtumor was found. The colonoscopy was otherwise normal. Biopsy showed moderately differentiated adenocarcinoma. His carcinoembryonic antigen (CEA) level is 1.8 ng/mL and computed tomography (CT) of the chest, abdomen, and pelvis showed no metastatic disease. Intraoperatively, no metastatic disease was noted. There was a mid-sigmoid tumor infiltrating a small part of the dome of the bladder with a loop of small bowel attached to the same area. What is the best way to manage this patient?