Stereotactic Body Radiotherapy (Sbrt) For Presacral Recurrence Of Rectal Cancer

Pelvic recurrence of recurrent rectal cancer is frequently not amenable to curative surgical salvage due to the location of these tumors and the high risk of morbidity from surgery. Patients often present with excruciating pain that significantly impair their quality of life. The goal of this study was to evaluate the safety and efficacy of stereotactic body radiotherapy (SBRT) in the management of presacral tumors as well as to report local control, and long-term survival rates. Between April 2003 and October 2008, 14 patients (3 females, mean age 63.1 ± 10.3 years) with presacral tumors from rectal adenocarcinoma primary were treated with SBRT at the University of Pittsburgh Cancer Institute. Patients with recurrent, unresectable or previously irradiated malignancies in the presacral region of the pelvis were subjects of this study. Presacral tumors were defined as tumors located in the anterior portion of the sacrum below the second segment (S2-S5). Eleven patients were treated with fractionated SBRT of 36 Gy in 3 fractions and 3 patients were treated with single fraction SBRT at a dose of 12, 16 or 18 Gy using the CyberKnife Robotic Radiosurgical System. Tumor response to treatment was assessed using modified RECIST criteria. Acute and late toxicities were assessed with Common Terminology Criteria Adverse Events (CTCAE) version 3.0. Local control (LC) and overall survival (OS) rates were calculated using Kaplan-Meier. Cox regression was used to model predictors of outcome. Pain control was also assessed. All patients had prior external beam radiotherapy [median dose 50.4 Gy (20 - 81 Gy)]. One patient (6.7%) received SBRT as part of a boost to primary therapy. The median tumor volume was 52.5 cc (19 - 110 cc) in the pelvic area involving either soft tissues (n = 8), bone (n = 1) or both (n = 2). With a median assessment of response follow-up of 4.9 months (1 - 16.3 months), 3 patients (21%) had a complete response (CR), 8 patients (57%) had stable disease (SD). For the entire group and an overall median follow-up of 16.5 months (6 - 69 months), the 1- and 2-year LC rates were 90.9% and 68.2%, respectively, and the 1- and 2-year OS rates were 90% and 78.8%, respectively. On multivariate analysis, no factors were significantly predictive of LC and OS. There were no grade 3 or 4 acute or late toxicities. Of 7 (50%) patients who initially presented with pain, 3 patients (21.4%) were pain free at completion of SBRT. SBRT for presacral recurrence of rectal adenocarcinoma is feasible and well-tolerated and appears to be an effective palliative strategy for symptomatic pelvic recurrences of rectal cancers.