Stereotactic body radiotherapy (SBRT) reirradiation for pelvic recurrence from colorectal cancer

Background and Objectives: When surgery is not adequate or feasible, stereotactic body radiotherapy (SBRT) reirradiation has been used for recurrent cancers. We report the outcomes of a series of patients with pelvic recurrences from colorectal cancer reirradiated with SBRT. Methods: The CyberknifeTM Robotic Stereotactic Radiosurgery system with fiducial based real time tracking was used. Patients were followed with imaging of the pelvis. Results: Four women and 14 men with 22 lesions were included. The mean dose was 25 Gy in median of five fractions. The mean prescription isodose was 77%, with a median maximum dose of 32.87 Gy. There were two local failures, with a crude local control rate of 89%. The median overall survival was 43 months. One patient had small bowel perforation and required surgery (Grade IV), two patients had symptomatic neuropathy (1 Grade III) and one patient developed hydronephrosis from ureteric fibrosis requiring a stent (Grade III). Conclusions: Local recurrence in the pelvis after modern combined modality treatment for colorectal cancer is rare. However it presents a therapeutic dilemma when it occurs; often symptomatic and eventually life threatening. SBRT can be a useful non-surgical modality to control pelvic recurrences after prior radiation for colorectal cancer. J. Surg.