A 56-year-old obese man with locally advanced distal rectal cancer is treated with total neoadjuvant chemoradiation therapy. His is a 45-pack-per-year smoker. Restaging reveals no sign of metastasis. Magnetic resonance imaging (MRI) rectal protocol reveals partial clinical response and flexible sigmoidsociopy that shows a 3-cm tumor involving the sphincteric complex. What is the best surgical approach in his care?