The Role of Prognostic Scoring Systems in Patients with Vertebral Metastases
A recently published study highlights the growing need for a reproducible, accurate, and broadly applicable method of identifying patients with spinal metastases who are appropriate candidates for surgical intervention.
Nicholas Shepard, MD, and Timothy Rapp, MD
Ahmed AK, Goodwin CR, Heravi A, Kim R, Abu-Bonsrah N, Sankey E, Kerekes D, De la Garza Ramos R, Schwab J, Sciubba DM. Predicting survival for metastatic spine disease: a comparison of nine scoring systems. Spine J. 2018;18(10):1804-1814. DOI 10.1016/j.spinee.2018.03.011
Acceptance for spine surgery as a viable option for treatment of patients with metastatic spine disease has grown significantly in the past 2 decades. One difficulty that persists is appropriate patient selection, whereby the benefits of proposed treatment are balanced against associated morbidity, perioperative risk, and predicted survival. Several prognostic scoring systems have been developed to aid surgeons in this decision process; however, their usefulness and accuracy remain controversial.
In this study, Ahmed et al reviewed the application of 9 common prognostic scoring systems to 176 patients who underwent surgical treatment for metastatic spine disease at a single institution. The primary outcome was survival probability as calculated by each scoring system, which was analyzed using receiver operating characteristic (ROC) analysis at 30, 90, and 365 days postoperatively. Secondary analysis was done to identify patient variables associated with survival.
Patients included in analysis were treated from 2003 to 2016, were between the ages of 18 and 100, underwent surgical resection of a metastatic spine lesion with pathologic confirmation of primary tumor etiology, and had known survival or follow-up. Indications for surgery included neurologic dysfunction, instability, and pain.
The 9 predictive scoring systems analyzed in this study included:
- Original Tokuhashi
- Revised Tokuhashi
- Original Bauer
- Modified Bauer
- Van der Linden
- Skeletal Oncology Research Group (SORG) Classic Scoring System
- SORG Nomogram
Patient variables analyzed included:
- Eastern Cooperation Oncology Group (ECOG) performance status
- Charlson Comorbidity Index
- Primary tumor
- Number of spinal metastases
- Presence of visceral metastases
- History of systemic therapy
- White blood cell (WBC) count
- Hemoglobin level
Among all patients included in the study, the SORG Nomogram demonstrated the highest accuracy at predicting 30-day (AUC 0.81) and 90-day (AUC 0.70) survival, while the original Tokuhashi system had the highest accuracy at predicting 365-day survival (AUC 0.78). The SORG Nomogram and Katagiri were the only scoring systems to have sufficient accuracy at predicting 30-, 90-, and 365-day survival. After excluding hematologic malignancies, the SORG Nomogram and Original Tokuhashi were still the most accurate at predicting 30- and 365-day survival, respectively. When stratified based on the primary tumor etiology, multiple scoring systems were found to achieve adequate accuracy at the various time points.
Specific factors associated with decreased survival included:
- Older age (HR 1.02, P=0.24)
- Poor ECOG performance status (HR 2.23, P<0.001)
- Primary cancer with poor prognosis (HR 2.6, P<0.001)
- Metastasis to the lungs or liver (HR 1.61, P=0.010)
- Brain metastasis (HR 2.38, P=0.001)
With advancements in treatment modalities and the resulting prolonged survival for multiple cancer diagnoses, the question of whether to operate on patients with spinal metastases has becoming increasingly prevalent. Patchell et al  reported on the benefits of surgical intervention for patients with spinal metastases, which has been confirmed in isolation or in combination with chemotherapy and/or radiation in a variety of patient populations with varying tumor types. Multiple scoring systems have been described to serve as prognostic calculators and guide the clinician in surgical decision making. To provide benefit, these scoring systems should be reproducible, accurate, and broadly applicable.
In this study, Ahmed et al highlight the variability in previously described prognostic scoring systems. Although the SORG Nomogram appeared to be the most accurate in predicting early survival, multiple scoring systems had equivalent or better accuracy when stratified by primary tumor etiology. The same was true for 365-day survival, with multiple scoring systems having sufficient accuracy. One strength of the study is that it stratifies based on primary tumor type, which may help to provide patient-specific prognostication dependent on the underlying diagnosis. This is particularly helpful given the clinical heterogeneity associated with spinal metastases.
Limitations of this study include its retrospective nature and single-institution approach, which impart selection, indication, and expertise biases. One commonly used outcome measure, the Karnofsky Performance Status, which has been validated in the assessment of spinal oncology patients, was also omitted from analysis. In addition, preoperative functional status and health-related quality of life outcomes were not included, which are important determinants in preoperative decision making and postoperative success.
With the rapid progression in treatment and understanding of primary tumor diagnoses and advancements in surgical technique and instrumentation, there is a growing need to appropriately identify those patients with spinal metastases who should undergo surgical intervention. This study reinforces the fact that a single prognostic scoring system may not be applicable across all patients or pathologies but can be a valuable resource when used at an individual level. Information obtained from these scoring systems regarding expected prognosis should be interpreted in conjunction with additional factors such as functional status and expected improvements in pain/quality of life when determining surgical indications.
Nicholas Shepard, MD, is an orthopedic surgery resident at NYU Langone Orthopedic Hospital, New York, New York. Timothy Rapp, MD, is an Associate Professor of Orthopedic Surgery and Chief of the Division of Orthopedic Oncology, at NYU Langone Orthopedic Hospital, New York, New York.
The authors have no disclosures relevant to this article
- Patchell RA, Tibbs PA, Regine WF, et al. Direct decompressive surgical resection in the treatment of spinal cord compression caused by metastatic cancer: a randomised trial. Lancet 2005;366:643-648.