Impact of the Spinal Instability Neoplastic Score on Surgical Referral Patterns and Outcomes

Background: The Spinal Instability Neoplastic Score (SINS) was developed to identify patients with spinal metastases who may benefit from surgical consultation. We aimed to assess the distribution of SINS in a population-based cohort of patients undergoing palliative spine radiotherapy (RT) and referral rates to spinal surgery pre-RT. Secondary outcomes included referral to a spine surgeon post-RT, overall survival, maintenance of ambulation, need for re-intervention, and presence of spinal adverse events. Methods: We retrospectively reviewed ct simulation scans and charts of consecutive patients receiving palliative spine rt between 2012 and 2013. Data were analyzed using Student’s t-test, Chi-squared, Fisher’s exact, and Kaplan-Meier log-rank tests. Patients were stratified into low (<7) and high (≥7) sins groups. Results: We included 195 patients with a follow-up of 6.1 months. The median SINS was 7. The score was 0 to 6 (low, no referral recommended), 7 to 12 (intermediate, consider referral), and 13 to 18 (high, referral suggested) in 34%, 59%, and 7% of patients, respectively. Eleven patients had pre-RT referral to spine surgery, with a surgery performed in 0 of 1 patient with sins 0 to 6, 1 of 7 with sins 7 to 12, and 1 of 3 with sins 13 to 18. Seven patients were referred to a surgeon post-RT with salvage surgery performed in two of those patients. Primary and secondary outcomes did not differ between low and high sins groups. Conclusion: Higher SINS was associated with pre-RT referral to a spine surgeon, but most patients with high sins were not referred. Higher SINS was not associated with shorter survival or worse outcome following RT.