Authors: Shashank Gandhi, MD; Shashank Gandhi, MD; Kevin Shah, MD; Daniel Schneider, MD; Maged Ghaly, MD; Ahmad Latefi, DO (Manhasset, NY)

Introduction: The Spinal Instability Neoplastic Score (SINS) helps assess the need for surgery for spinal metastatic disease; however, for potentially unstable lesions (SINS 7-12) the benefit is unclear. The role of surgery is palliative to improve quality of life as prognosis is dictated by systemic disease. Therefore, allowing patients to return to daily life while limiting hospitalization is paramount. This study assesses the role of surgery in reducing 90-day-admission for potentially unstable spinal lesions. Methods: Patients with lesions SINS 7-12 treated for spinal metastatic disease from 2010-2015 retrospectively assessed. Patients were grouped as no surgery or surgery prior to radiotherapy. 90-day-admissions rates after radiotherapy was assessed in each group, along with the impact of the following factors: high grade epidural spinal cord compression (ESCC), radiosensitivity, local control, development of fractures, and hypofractionation. Results: 61 patients with SINS 7-12 were treated: 44 in no surgery and 17 in surgery prior to radiotherapy. 90-day-admission rates were higher in the nonsurgical group (54.5% vs. 5.9%, p=0.001). Spine-pathology related admissions were 18.2% nonsurgical vs. 0% surgical groups. The 1 surgical admission was for ileus. Counterintuitively, ESCC was associated with lower admission (13.3% vs. 50.0%, p=0.012); however, is explained as high ESCC correlated to greater likelihood for surgery (58.9% vs. 11.4%, p<0.001). Local control did not impact 90-day-admission (48.6% vs. 29.2%, p=0.131), nor did tumor radiosensitivity (45.5% vs. 35.8%, p=0.441). The development of fractures had higher admission (100% vs 37.9%, p=0.033). When controlling for above factors only surgery and development of fractures correlated to reduced 90-day-admission (p=0.019 and p=0.040). The nonsurgical group had greater fractures (6.82% vs. 0%). Conclusions: Surgery for potentially unstable metastasis reduces 90-day-admission rates. Development of fractures increases 90-day-admission rates, likely due to pain. Local control does not reduce admission, showing that treatment should focus on quality of life rather than solely tumor control.