A 79-year-old man diagnosed with rectal cancer and underwent preoperative chemoradiotherapy. After chemoradiotherapy, the patient underwent abdominoperineal resection. Postoperative pathological examination confirmed pathological complete response. Postoperatively, the patient developed a pelvic abscess due to wound infection from the anal fistula, which required drainage and antibiotic therapy. Treatment options that include a watch and wait approach are required in cases of resectable lower rectal cancer with a high risk of local recurrence that has shrunk after preoperative chemoradiation.