Stereotactic body radiotherapy as a primary treatment for spinal metastasis: a single institution experience.

Abstract

To investigate the clinical outcome including efficacy and safety of stereotactic body radiotherapy (SBRT) in management of spinal metastasis. Between 2010 and 2017, 26 patients with 32 metastatic spine lesions treated with SBRT were retrospectively reviewed. Local control (LC), overall survival (OS), prognostic factors and toxicity were analyzed. There were 15 female and 11 male patients (median age, 62 years; range 27 to 88 years). 32 metastatic spine lesions were treated with SBRT. The most frequent lesions treated were metastatic tumours of the lung (n=19), other primary histologies were prostate (n=4), breast (n=3), sarcoma (n=2), hepatocellular carcinoma (n=1), renal cell carcinoma (n=1), stomach (n=1), nasopharyngeal carcinoma (n=1). Thoracic spine was the most common site treated (n=18), followed by lumbosacral spine (n=12) and cervical spine (n=2). The most common dose fractionation used was 24 Gy in 3Fr. The median EQD2/10 Gy was 36 Gy (range, 34.7-59.7 Gy). The median planning target volume (PTV) was 50 cc (range, 10.4-194 cc). The median follow up was 23.4 months (range, 3-103 months). For the entire cohort, local tumour control (LC) at 1 year and 2 years were 83% and 71% respectively. The median OS was 30.6 months. The OS at 1 year and 2 years were 88% and 59% respectively. On univariate analysis for OS, presence of visceral metastases (HR 11.13, P=0.001), uncontrolled primary disease (HR 4.57, P=0.02) and presence of more than 3 vertebral metastasis (HR 5.50, P=0.04) were corelated with worst outcomes. On multivariate analysis for OS, only presence of visceral metastasis remained significant (HR 23.99, P=0.002). Acute toxicity mainly pain flare occurred in 16% of the treated lesions that can be managed with analgesics and steroid. Other adverse events were rare and no radiation induced myelopathy reported. This study reports SBRT is a safe and effective treatment for spinal metastasis. Prognostic factors were identified to guide patient selection that would benefit from this treatment.