Vertebral compression fracture risk after stereotactic body radiotherapy for spinal metastases

Abstract

<jats:sec> <jats:title>Object</jats:title> <jats:p>The aim of this study was to identify potential risk factors for and determine the rate of vertebral compression fracture (VCF) after intensity-modulated, near-simultaneous, CT image–guided stereotactic body radiotherapy (SBRT) for spinal metastases.</jats:p></jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>The study group consisted of 123 vertebral bodies (VBs) in 93 patients enrolled in prospective protocols for metastatic disease. Data from these patients were retrospectively analyzed. Stereotactic body radiotherapy consisted of 1, 3, or 5 fractions for overall median doses of 18, 27, and 30 Gy, respectively. Magnetic resonance imaging studies, obtained at baseline and at each follow-up, were evaluated for VCFs, tumor involvement, and radiographic progression. Self-reported average pain levels were scored based on the 11-point (0–10) Brief Pain Inventory both at baseline and at follow-up. Obesity was defined as a body mass index ≥ 30.</jats:p></jats:sec> <jats:sec> <jats:title>Results</jats:title> <jats:p>The median imaging follow-up was 14.9 months (range 1–71 months). Twenty-five new or progressing fractures (20%) were identified, and the median time to progression was 3 months after SBRT. The most common histologies included renal cancer (36 VBs, 10 fractures, 10 tumor progressions), breast cancer (20 VBs, 0 fractures, 5 tumor progressions), thyroid cancer (14 VBs, 1 fracture, 2 tumor progressions), non–small cell lung cancer (13 VBs, 3 fractures, 3 tumor progressions), and sarcoma (9 VBs, 2 fractures, 2 tumor progressions). Fifteen VBs were treated with kyphoplasty or vertebroplasty after SBRT, with 5 procedures done for preexisting VCFs. Tumor progression was noted in 32 locations (26%) with 5 months' median time to progression. At the time of noted fracture progression there was a trend toward higher average pain scores but no significant change in the median value. Univariate logistic regression showed that an age &gt; 55 years (HR 6.05, 95% CI 2.1–17.47), a preexisting fracture (HR 5.05, 95% CI 1.94–13.16), baseline pain and narcotic use before SBRT (pain: HR 1.31, 95% CI 1.06–1.62; narcotic: HR 2.98, 95% CI 1.17–7.56) and after SBRT (pain: HR 1.34, 95% CI 1.06–1.70; narcotic: HR 3.63, 95% CI 1.41–9.29) were statistically significant predictors of fracture progression. On multivariate analysis an age &gt; 55 years (HR 10.66, 95% CI 2.81–40.36), a preexisting fracture (HR 9.17, 95% CI 2.31–36.43), and baseline pain (HR 1.41, 95% CI 1.05–1.9) were found to be significant risks, whereas obesity (HR 0.02, 95% CI 0–0.2) was protective.</jats:p></jats:sec> <jats:sec> <jats:title>Conclusions</jats:title> <jats:p>Stereotactic body radiotherapy is associated with a significant risk (20%) of VCF. Risk factors for VCF include an age &gt; 55 years, a preexisting fracture, and baseline pain. These risk factors may aid in the selection of which spinal SBRT patients should be considered for prophylactic vertebral stabilization or augmentation procedures. Clinical trial registration no.: NCT00508443.</jats:p></jats:sec>

The use of spine stereotactic radiosurgery for oligometastatic disease

“…In addition, 16% of patients developed compression fractures, consistent with previous reports. 2,24 There have been variable reports on the dose limitation to the spinal cord using SSRS, with 1 recent analysis reporting a ≤ 5% risk of myelopathy with a 12.4 Gy Dmax, 25 or even no reported myelopathy with a Dmax of 14 Gy. 33 In general, we limit the spinal cord receiving 10 Gy to 0.01 cm 3 or less for single-fraction SSRS.…”

Stereotactic Radiosurgery for the Treatment of Primary and Metastatic Spinal Sarcomas

“…[22][23][24][25][26] This questionnaire has also been used in the study of SRS-induced vertebral fractures, metastatic bone disease, and sarcoma resections. [27][28][29] Patients rate their worst, current, and average pain at the time of BPI collection (each ranging from 0 to 10) at the treatment site of interest. 30 ''Current'' pain at the time of BPI collection during clinical follow-up was used to evaluate pain relief and symptomatic failure after SRS.…”

Comparison of four techniques for spine stereotactic body radiotherapy: Dosimetric and efficiency analysis

“…This can potentially increase plan complexity and technical demand on the delivery system 14. Aside from radiation myelopathy, treatment‐related vertebral compression fracture (VCF) is a known complication from SBRT 15, 16. It remains possible that the dose heterogeneity (i.e., hotspots) within the vertebral body contributes to the risk of VCF.…”