Top Line: Does the use of a CTV margin reduce the risk of local recurrence after SBRT for non-spine bone metastases?
The Study: We know that not using an elective CTV in spine SBRT increases the risk of local recurrence. A recent meta-analysis recommended a 0-5mm CTV margin when MRI or PET-CT are used for planning and a 5-10mm CTV margin with CT alone. This study took a look back at 193 patients treated with SBRT for 261 non-spine bone metastases. A CTV margin was used in roughly a third (30.4%) of patients, and the most common CTV margin was 5 mm. The authors defined a local recurrence as one that occurred within 2 cm of the GTV regardless of whether a CTV was originally used. Local control was 85.2% at 1 year. At 2 years, the cumulative incidence of local recurrence was 22.8%. Of those recurrences, only 28% would have been encompassed by a 2 cm CTV margin around the original GTV. The use of a CTV margin was not associated with a lower risk local recurrence.
TBL: In this retrospective study, relatively small CTV margins (typically 5 mm) did not significantly reduce local recurrence after SBRT for non-spine bone metastases. However, most recurrences wouldn’t have been covered by even larger margins. | Bodson, Radiother Oncol 2026
The Study: We know that not using an elective CTV in spine SBRT increases the risk of local recurrence. A recent meta-analysis recommended a 0-5mm CTV margin when MRI or PET-CT are used for planning and a 5-10mm CTV margin with CT alone. This study took a look back at 193 patients treated with SBRT for 261 non-spine bone metastases. A CTV margin was used in roughly a third (30.4%) of patients, and the most common CTV margin was 5 mm. The authors defined a local recurrence as one that occurred within 2 cm of the GTV regardless of whether a CTV was originally used. Local control was 85.2% at 1 year. At 2 years, the cumulative incidence of local recurrence was 22.8%. Of those recurrences, only 28% would have been encompassed by a 2 cm CTV margin around the original GTV. The use of a CTV margin was not associated with a lower risk local recurrence.
TBL: In this retrospective study, relatively small CTV margins (typically 5 mm) did not significantly reduce local recurrence after SBRT for non-spine bone metastases. However, most recurrences wouldn’t have been covered by even larger margins. | Bodson, Radiother Oncol 2026