As reviewed in this issue of The ASCO Post, Sahgal et al reported a multi-institutional analysis aimed at clarifying the risk of developing either new or progressive vertebral body compression fractures following high-dose spinal stereotactic body radiation therapy. In the period studied, they encountered 57 vertebral compression fractures out of 410 vertebrae that were treated with such therapy (14%). They report that vertebrae at risk for collapse included those with a baseline vertebral compression fracture, lytic disease, or malalignment, and that caution should be taken when treating such lesions with doses ≥ 20 Gy/fraction.
I tend to look at this well-written paper in a positive light in that there were only 57 vertebral compression fractures out of the 410 segments treated, and of those 57 vertebral compression fractures, only 24 required further interventions, of which 18 had minimally invasive procedures. Thus, the majority of the vertebral compression fractures encountered required no further intervention.
The authors comment that high-dose single-fraction stereotactic body radiotherapy (≥ 20 Gy/fraction) may be exposing patients to prohibitive risks of vertebral compression fracture. I believe we are not exposing patients to prohibitive risks of vertebral compression fracture.
It can be agreed upon that the ultimate goal in treating spine metastasis with high-dose single-fraction stereotactic body radiotherapy is to provide local control regardless of tumor histology. One can argue that dealing with the increased risk of a vertebral compression fracture is perhaps a small price to pay in the setting of local tumor control, knowing that most of these vertebral compression fractures might require no further intervention, and those that do can often be dealt with in a minimally invasive manner with cement augmentation with or without percutaneous instrumentation.
To put it another way, it is usually easier to handle a vertebral compression fracture in the setting of nonviable tumor treated with high-dose single-fraction stereotactic body radiotherapy (≥ 20 Gy/fraction) than it is to treat a recurrent metastasis that has been treated with < 20 Gy/fraction.
In summary, this paper further identifies risks for vertebral compression fracture associated with spine stereotactic radiosurgery, especially regarding lesions treated with high-dose single-fraction stereotactic body radiotherapy (≥ 20 Gy/fraction). I contend that the risk of vertebral compression fracture associated with such treatment is outweighed by the benefit of local tumor control and that it is far easier to palliate a vertebral compression fracture without tumor progression than it is to deal with the complications associated with active tumor recurrence—which frequently include vertebral compression fractures anyway. ■
Dr. Lis is Director of Interventional Neuroradiology, Memorial Sloan-Kettering Cancer Center, New York.
Disclosure: Dr. Lis has given educational lectures for Medtronic.