Radiation-associated rectal cancer: report of four cases

Radiation-associated rectal cancer is a remarkable clinical entity. We demonstrate 4 patients (mean age 68 years, range 63-74) who had undergone pelvic radiotherapy for cervical cancer. We indicate some characteristics of radiation-associated rectal cancer.

Two patients had received intracavitary and external pelvic radiotherapy, while the remaining 2 had external pelvic radiotherapy following hysterectomy. The mean total radiation dose was 63 Gy, though radiation dose information was not available for 1 patient. Colorectal cancer developed at a mean time of 20.7 years (range 11-30) after radiation therapy. All patients presented with chronic radiation colitis, and 3 demonstrated abnormal tumor markers. Colonoscopy revealed an ulcerative, localized well-differentiated adenocarcinoma of the rectosigmoid colon in 1 patient, and diffusely infiltrating cancers of the lower rectum, one signet-ring cell carcinoma and two mucinous carcinomas in the remaining 3. One case was stage I, 2 were stage IIIa, and the remaining case was stage IV. Three patients underwent abdominoperineal resection. The remaining patient was felt to be inoperable. The colorectal wall demonstrated the changes of chronic radiation injury. Two patients died within a short time because of their advanced cancers.

Radiation-associated rectal cancer has a tendency to be diagnosed in the advanced stage and to have a poor prognosis. A literature review and our case report suggest that since there are no reliable clinical or laboratory indicators of the presence of a curable colorectal cancer in the setting of chronic radiation proctocolitis, surveillance with a colonoscope should be done 10 years after irradiation in patients with previous pelvic radiotherapy.