A Retrospective Cohort Analysis Evaluating the Utility of the Spinal Instability Neoplastic Score (SINS) in Screening for Spinal Instability and Vertebral Compression Fracture Risk in Plasma Cell Neoplasm and Lymphoma Lesions.

Abstract

Background context: Spinal column tumors with Spinal Instability Neoplastic Scores (SINS) suggesting instability often trigger referrals to spine surgeons. Plasma cell lesions and lymphoma are highly radiosensitive histologies, and may re-ossify after radiation therapy. The SINS score, designed to assess the need for surgical stabilization for spinal neoplasms, may therefore overestimate instability in patients with these radiosensitive histologies.

Purpose: Herein we seek to determine if the SINS score is significantly correlated with lesion instability and vertebral compression fracture progression in patients with plasma cell neoplasms or lymphoma of the spine.

Study design: This was a retrospective single-institution cohort analysis.

Patient sample: Patients with spinal plasma cell or lymphoma lesions with identifiable primary lesions were found by querying our institutional electronic medical record from 2010-2024. All patients were at least 18 years of age.

Outcome measures: Demographics, comorbidities, symptoms, radiation data, surgical data, and imaging data were collected. Outcomes included development of spinal instability, new or progressive vertebral compression fracture, and follow-up neurological status.

Methods: Multivariable logistic regressions were used to evaluate categorical outcomes, while Kaplan-Meier analysis was utilized to assess time to mortality.

Results: 240 patients were identified with a mean SINS of 9.79. 23 patients had lesions classified as stable (SINS 0-6, 9.8%), 183 had lesions classified as possibly unstable (SINS 7-12, 76.3%), and 34 had lesions classified as unstable (SINS 13-18, 14.2%). 27 patients underwent surgical management (2 SINS stable, 20 possibly unstable, and 5 unstable), with a 90-day reoperation rate of 11.1% and a 90-day readmission rate of 29.6%. At 3-month follow-up, factors associated with development of instability were higher total SINS score (odds ratio (OR) 1.38, p < 0.001), SINS unstable lesions compared with possibly unstable lesions (OR 2.69, p = 0.028), younger age (OR 0.98 per year, p < 0.001), and higher radiation biologically effective dose (OR 1.03, p < 0.001). Meanwhile, factors associated with new or progressive vertebral compression fracture were higher total SINS score (OR 1.45, p < 0.001), SINS unstable lesions compared with possibly unstable (OR 3.59, p = 0.002), possibly unstable lesions compared with stable (OR Stable 0.22, p = 0.029), and increased age (OR 1.01 per year, p < 0.001), while larger baseline VB height (OR 0.91, p < 0.001) and bisphosphonate or RANK-ligand inhibitor use (OR 0.61, p = 0.009) were protective. SINS was not significantly associated with follow-up neurological status.

Conclusions: SINS is a useful prognostic factor for the development of instability and new or progressive vertebral compression fracture in patients with plasma cell or lymphoma spinal lesions. However, current thresholds used to define the possibly unstable category may not reliably reflect true instability in these radiosensitive lesions. Surgical decision-making paradigms must be carefully assessed in these patients, given the significant rates of morbidity associated with surgical management of these lesions.