Outcomes of SBRT for Symptomatic Benign Tumors of the Spine

Abstract

<h3>Purpose/Objective(s)</h3> Benign spinal tumors (BSTs) are rare, present across the age spectrum, and may be associated with significant neurologic morbidity. While conservative medical management may be sufficient, many patients experience progression requiring escalated interventions, including surgery. Stereotactic body radiotherapy (SBRT) may be an additional effective management approach for BSTs in the upfront or adjuvant setting. We report our institutional experience of SBRT in management of BSTs. <h3>Materials/Methods</h3> Patients with symptomatic BSTs treated at a single institution with SBRT from 2010-2020 were retrospectively reviewed. Treatment outcomes including symptom and radiographic response were recorded from the electronic health record and presented with descriptive statistics and analyzed by chi-square and univariate logistic regression. <h3>Results</h3> In total, 31 patients with 36 symptomatic BSTs receiving SBRT were identified. Median age at presentation was 57 (IQR: 43-63). Pain was the primary symptom at presentation (92%), followed by paresthesias (28%) and weakness (19%). Histologies were schwannoma (39%), meningioma (33%), hemangioma (22%), and other (6%). Treated spine levels were cervical (44%), thoracic (36%), lumbosacral (19%). 47% of patients had prior surgery at the treated site. Median SBRT prescription dose was 25 Gy (range: 18-40 Gy in 3-5 fractions) treated on consecutive days. Median PTV was 6.0 cc (IQR: 3.5-19.4 cc). Median thecal sac max (0.03 cc) dose was 26.2 Gy (range 0.4-30.2). Interval imaging cadence following treatment was q3-6 months. Median radiographic f/u was 28 months (IQR 9-60). 58% of patients reported durable symptom improvements. 44% of patients experienced acute toxicity from treatment including fatigue, esophagitis, regional pain flare (all grade≤2). One patient developed symptomatic radiation-induced mid-thoracic level myelitis at 6 mo following SBRT with neurologic improvement following protracted (>3 mo) steroid administration with taper. 50% of patients demonstrated radiographic response at last follow-up while 3% showed progression and 47% remained stable. There was no significant association between treatment response or acute/late toxicity and lesion location, dose, or prior surgery. <h3>Conclusion</h3> SBRT for BST, as definitive therapy or for salvage following surgery, was largely effective and safe, with limited high-grade toxicity. Most patients demonstrated symptomatic and/or radiographic response following spine-lesion directed SBRT.