[A case of radiation-induced rectal cancer].

We report a case of radiation-induced rectal cancer, which is thought to originate from dysplasia due to radiation colitis. The patient is a 73 year-old woman, who underwent radical hysterectomy and radiotherapy for uterine cervical cancer 31 years ago. She visited to our hospital complaining of hematochezia. Colonoscopy in January 2004 disclosed redness of the rectal mucosa accompanied with contact bleeding and pathological study of the biopsy specimen revealed severe dysplasia. However, colonoscopy showed an ulcerative lesion of the rectum in December 2004, and pathological findings of the biopsy specimen disclosed moderately differentiated adenocarcinoma. She underwent a rectal resection in January 2005. Pathological study of resected specimen revealed fibrous change induced by radiation. Predominant histological type of the tumor was moderately differentiated carcinoma followed by well differentiated type. However, multiple dysplasias were found around the main tumor or in the mucosa which was treated with radiotherapy.