Pelvic re-irradiation using stereotactic ablative radiotherapy (SABR): A systematic review

Background and purpose: To perform a systematic review regarding the use of stereotactic ablative radiotherapy (SABR) for the re-irradiation of recurrent malignant disease within the pelvis, to guide the clinical implementation of this technique. Material and methods: A systematic search strategy was adopted using the MEDLINE, EMBASE and Cochrane Library databases. Results: 195 articles were identified, of which 17 were appropriate for inclusion. Studies were small and data largely retrospective. In total, 205 patients are reported to have received pelvic SABR re-irradiation. Dose and fractionation schedules and re-irradiated volumes are highly variable. Little information is provided regarding organ at risk constraints adopted in the re-irradiation setting. Treatment appears well-tolerated overall, with nine grade 3 and six grade 4 toxicities amongst thirteen re-irradiated patients. Local control at one year ranged from 51% to 100%. Symptomatic improvements were also noted. Conclusions: For previously irradiated patients with recurrent pelvic disease, SABR re-irradiation could be a feasible intervention for those who otherwise have limited options. Evidence to support this technique is limited but shows initial promise. Based on the available literature, suggestions for a more formal SABR re-irradiation pathway are proposed. Prospective studies and a multidisciplinary approach are required to optimise future treatment.