A 50-year-old man had a 1-cm sessile sigmoid polyp removed with cold snare technique in one piece and tattooed distally during screening colonoscopy. Final pathology report showed a sessile serrated adenoma with a focus of well-differentiated adenocarcinoma invading the lower third of the submucosa but not invading the muscularis propria. There is no lymphovascular invasion. Staging with computed tomography of the chest, abdomen, and pelvis is negative for metastatic disease and carcinoembryonic antigen level is normal. What is the most acceptable next step for this patient?