A 68-Year-Old Woman Is Evaluated Because of Rectal Bleeding That

A 68-year-old woman is evaluated because of rectal bleeding that began recently and a sense of fullness in the rectum. Flexible sigmoidoscopy shows a mass 11 cm from the anus, and biopsy reveals adenocarcinoma. The patient is referred to a colorectal surgeon, and a low anterior resection is performed. The primary tumor, a 4-cm moderately differentiated adenocarcinoma, penetrates the bowel wall. No lymph nodes are involved. What is the most appropriate next step in this patient"s management?

A) No chemotherapy or radiation therapy; annual flexible sigmoidoscopy
B) Postoperative adjuvant chemotherapy and pelvic radiation therapy
C) Postoperative pelvic radiation therapy
D) Complete colonoscopy within the first year, repeated every 3 to 5 years