Prospective Validation of An Inpatient Metastatic Spine Neoplasm Score To Assess the Optimal Radiation Therapy Intervention Modality

Summary: Radiation has long been essential in treating metastatic spine disease, traditionally via conventional external beam radiation therapy (EBRT), but with stereotactic body radiation therapy (SBRT) markedly increasing in popularity over the past two decades. Most SBRT vs EBRT data involves outpatients, with little data guiding management of inpatients with metastatic spine disease. Recently, an Inpatient Metastatic Spine Score evaluated retrospectively produced promising results regarding its ability to select patients with prognoses favorable enough to benefit from the durability advantages of SBRT over EBRT, with scores of 0-3 warranting recommendation of SBRT over EBRT compared with scores of 4-7 yielding median survival < 90 days. This study represents prospective evaluation of this algorithm to further assess its potential utility in this patient population. From July-November 2023, 11 spine metastases referred for inpatient Radiation Oncology consultation were prospectively assessed on an IRB-approved protocol; all were anatomically eligible for SBRT consideration. Patients were assessed according to the Inpatient Metastatic Spine Score consisting of: age at admission (60+ vs younger), duration of metastatic disease diagnosis (6+ months vs sooner), on active systemic therapy/refractory to systemic therapy (yes/no), additional non-spine metastatic focus (yes/no), severe malnutrition of chronic disease (yes/no), brain metastases (yes/no), and admission for symptomatology besides spine/back pain (yes/no). Each category was scored as a 0 (no) or 1 (yes); a cumulative score was derived for each patient. Patients with scores of 0-3 were recommended for SBRT, while patients with scores 4-7 were recommended for EBRT or no radiation therapy. The timeframe from inpatient consultation to death/hospice referral was recorded for each patient and then correlated with the cumulative score. Fisher’s test (p< 0.05 defining significance) was used for statistical analysis. Median age was 68.5 years (mean=67 years; range=44-81), with the most common primary tumor histology being breast (n=5), lung (n=3) and prostate (n=2). Patients with a score of 0-3 (n=5) had median survival of 278 days (mean=313.6; range=277-396), compared with scores of 4-7 (n=6) having median survival of 37.5 days (mean=114.2 days; range=2-317); this difference was statistically significant (p=0.0146). Five patients remained alive at time of analysis. Prospective validation of the Inpatient Metastatic Spine Score reveals the prognosis of patients with scores of 4-7 have median survival too brief to benefit from the durability advantages of SBRT over EBRT, while scores of 0-3 have a prognosis long enough to benefit from SBRT. These results concur with previous retrospective evaluation, and indicate that the Inpatient Metastatic Spine Score is a reliable tool for determining which inpatients with spine metastases are appropriate for SBRT over EBRT. Shearwood McClelland III, drwood@post.harvard.edu (Presenting Author) - University Hospitals Seidman Cancer Center, Case Western Reserve University School of Medicine