Rectal leiomyosarcoma: a rare and long-term complication of radiation therapy.

Leiomyosarcoma of the rectum can develop as a late complication in patients with a history of pelvic irradiation. We report the case of a patient who developed rectal leiomyosarcoma 13 years after receiving radiation for treatment of a stage 2 squamous cell cancer of the anus. This was detected on physical examination. Based on a discussion with the patient, we decided to manage conservatively. Overall, leiomyosarcomas constitute 5-12% of radiation-induced sarcomas. Rectal leiomyosarcoma is rare, accounting for 0.1-0.5% of all malignant tumours of the rectum. As radiation therapy plays a major role in the management of anal cancer, it is important that clinicians are aware of the possible development of radiation-induced sarcomas that may occur decades after initial management.