Predictive Value of the Spinal Instability Neoplastic Score for Survival and Ambulatory Function After Surgery for Metastatic Spinal Cord Compression in 110 Patients with Prostate Cancer.

Abstract

We retrospectively analyzed Spinal Instability Neoplastic Score (SINS) in 110 patients with prostate cancer operated for metastatic spinal cord compression (MSCC). We aimed to investigate the association between SINS and clinical outcomes after surgery for MSCC in patients with prostate cancer. The SINS is a useful tool for assessing tumor-related spinal instability, but its prognostic value regarding survival and neurological outcome is still controversial. We analyzed 110 consecutive patients with prostate cancer who underwent surgery for MSCC. The patients were categorized according to their SINS. Patients with castration-resistant prostate cancer (CRPC, n = 84) and those with hormone-naïve disease (n = 26) were analyzed separately. In total, 106 of 110 patients met the SINS criteria for potential instability or instability (scores 7-18). The median SINS was 10 (range 6-15) for patients with CRPC and 9 (7-16) for hormone-naïve patients. In the CRPC group, the SINS was classified as stable (score 0-6) in 4 patients, as potentially unstable (score 7-12) in 70 patients, and as unstable (score 13-18) in 10 patients. In the hormone-naïve group, 22 patients met the SINS criteria for potential instability and 4 patients for instability. There was no statistically significant difference in the overall risk for death between the SINS potentially unstable and unstable categories (adjusted hazard ratio 1.3, P = 0.4), or in the risk of loss of ambulation 1 month after surgery (adjusted odds ratio 1.4, P = 0.6). The SINS is helpful in assessing spinal instability when selecting patients for surgery, but it does not predict survival or neurological outcomes. Patients with a potential spinal instability benefit equally from surgery for MSCC as do patients with spinal instability.Level of Evidence: 3.