Double shot.

The best described spine stereotactic body radiation (SBRT) regimens consist of a single fraction. Here we have a report of nearly 150 patients from Sunnybrook describing spine SBRT of 24 Gy in 2 sequential daily fractions. Target delineation was consistent with consensus guidelines plus a 2 mm PTV margin. A 1.5 mm PRV margin was used around the spinal cord, which could receive a maximum dose of 14.5 Gy total prior to 2012 and up to 17 Gy thereafter. The rate of local failure at 1 and 2 years was 10% and 18%, respectively, with a median time to failure of 9 months. For lesions without epidural extension, those rates were both <10%. Importantly, there were no major neurological toxicities. The rates of vertebral compression fracture were 9 and 14% at 1 and 2 years, which compare favorably to single fraction series. This particular regimen is currently being compared to 20 Gy in 5 fractions in the ongoing SC-24 trial. TBL: 24 Gy in 2 fractions appears to be a safe and effective regimen for spine SBRT. | Tseng, Int J Radiat Oncol Biol Phys 2018