Postoperative pelvic irradiation.
D000230:Adenocarcinoma / Q000532:radiotherapy*; D006801:Humans; D009364:Neoplasm Recurrence, Local / Q000517:prevention & control*; D011184:Postoperative Period; D012004:Rectal Neoplasms / Q000532:radiotherapy*; D012811:Sigmoid Neoplasms / Q000532:radiotherapy*