Introduction: Spine Radiosurgery (SRS) has become an important tool in the management of primary and metastatic spine tumors. This study was performed to examine the factors that may increase fracture risk in patients who undergo SRS.
Methods: A review of 662 SRS treatments performed on 529 consecutive patients was performed. A majority of the patients (56%) had prior radiation therapy, were men (53%), had a KPS greater than 80 (76%), had no prior bisphosphonate administration (74%), and were neurologically intact—ASIA E (88%). The most common primary malignancy was breast (23%) followed by lung (16%). The majority of lesions were osteolytic (63%); 20% of patients had preexisting compression fractures at the treated level. The most common reason for SRS was pain 73%, and 66% underwent treatment to a single vertebrae. The median prescription dose was 24 Gy (8 to 65 Gy), and the median target volume was 31.6 cc (range 1 to 721 cc). Median follow-up was 9.5 months (3 to 92 months).
Results: Three percent of patients developed a new fracture after SRS while 4% developed progression of a previously existing fracture. The following factors were found to have a statistically significant correlation with post-SRS fractures (p<0.02): 2 or more levels treated (11% versus 5%), osteolytic lesions, paraspinal involvement (12.8% versus 4.6%), target volume greater than 45 cc (10.5% versus 4.4%), maximum dose greater than 41 Gy (10.7% versus 3.7%). The following factors were not found to be significant: administration of bisphosphonates, spine level, prior surgery, or single fraction (versus hypofractionated) treatment.
Conclusions: Vertebral fracture after SRS is at least twice as likely when two or more levels are treated, there is paraspinal involvement, target volume is greater than 45 cc, or dose is greater than 41 Gy. This information can be used to counsel patients or guide pre-SRS cement augmentation decisions.
Patient Care: 1) Allow clinicians to educate patients regarding the vertebral body fracture risk in after spine radiosurgery based on their individual risk factors.
2) Modify treatment to avoid vertebral body fractures after spine radiosurgery.
Learning Objectives: By the conclusion of the session, participants should be able to 1)Identify factors that increase the risk for vertebral compression fractures after SRS 2) Modify clinical practice to avoid increasing fracture risk in patients undergoing CNS.