A three-dimensional approach for re-irradiation of recurrent colorectal adenocarcinoma.

A large number of patients with resected rectal cancer will develop a symptomatic pelvic recurrence despite previous adjuvant radiation therapy. Re-irradiation after previous high dose radiation therapy carries an increased risk of complications in the normal tissues of the pelvis. However, other treatment modalities are not likely to provide a palliative benefit. Previous studies have shown that re-irradiation may be feasible and may palliate the patient. As minimal data is available on the toxicity of additional radiation therapy, this approach would be considered only when there is no other alternative for effective therapy and in the face of progressive and severe symptoms. With the use of three dimensional (3-D) treatment planning, portals can be designed to limit dose to previously irradiated critical structures while minimizing the risk of treatment related complications.