Clinical StudyAssessing the utility of a prognostication model to predict 1-year mortality in patients undergoing radiation therapy for spinal metastases
Introduction
An estimated 5%–10% of all cancer patients experience spinal metastases over the course of their disease, with the most common tumors being those of the breast, prostate, and lung [1]. These lesions are often accompanied by significant morbidity and present with symptoms including back pain, compression fracture, radiculopathy, and myelopathy. Treatment decisions can be complex and frequently involve a multidisciplinary team of surgeons, medical oncologists, and radiation oncologists. For many patients, radiation therapy (RT) is the primary treatment for spine metastases, particularly in patients who are not surgical candidates and have a limited life expectancy [2], [3], [4]. Accurately assessing prognosis is critical in identifying optimal candidates for spinal RT, as well as in determining the suitable total dose and length of treatment regimens.
Currently, validated prognostic tools used to predict mortality following spinal RT for metastatic disease in the general population are limited, with most validated models in patients with spinal cord compression [5], [6], [7], [8]. In patients with spinal metastases treated with surgery, a number of clinical schemes have been developed to predict postoperative mortality and to guide treatment decisions. These schemes take into account clinical factors including tumor characteristics, the extent of the metastatic disease, neurologic symptoms, and radiological data [9], [10], [11], [12]. Among these prognostic tools, the modified Bauer score—reflecting tumor histology and the presence of visceral and skeletal metastases—is frequently used by spine surgeons and has demonstrated predictive value for mortality among surgical candidates, with a lower score predicting for worse survival [13]. Recently, Ghori et al. sought to further improve on the predictive value of the modified Bauer with the development of the New England Spinal Metastasis Score (NESMS) to predict 1-year survival following surgery for spinal metastasis [14]. The NESMS is composed of three factors: preoperative albumin, ambulatory status, and modified Bauer score, with the total score ranging from 0 to 3. In the cohort of 318 patients used to develop the scoring system, the NESMS accounted for 74% of the variation in 1-year survival, compared with the modified Bauer score alone, which predicted only 64% of the variation in 1-year survival. The NESMS has subsequently been validated in independent cohorts as a more robust predictor of 1-year survival following surgery for spinal metastases, again with a lower score predicting for worse survival [15], as well as short-term outcomes including 30- and 90-day mortality [16], [17].
Although these published results have helped clinicians to better prognosticate in surgical patients, little is known about the utility of such clinical tools among patients undergoing RT alone for spinal metastases. Given that the NESMS evaluates patient and disease characteristics that affect post-treatment mortality outcomes in both surgical and non-surgical patients, we sought to validate the predictive value of the NESMS in a non-operative population. The purpose of the present study is to assess the applicability of the NESMS model to predict 1-year survival among patients treated with RT alone for spinal metastases.
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Materials and methods
This investigation was approved by the DFHCC Institutional Review Board. Patients treated with RT for spinal metastasis at Brigham and Women's Hospital/Dana Farber Cancer Institute from January 2008 to December 2013 were retrospectively reviewed. Patients were included if they were treated with RT alone (without surgery) for metastatic disease to the spine and had complete follow-up through 1-year post-treatment completion (including the documented date of death during this period, if
Patient demographics and clinical characteristics
A total of 290 patients met the inclusion and the exclusion criteria and were included in this analysis. The median follow-up was 57.2 months among patients who were still alive as of this analysis. Eight patients who underwent conventional RT alone were excluded as they were lost to follow-up before the 1-year post-treatment completion. Patient demographics including age, gender, race, performance status, tumor histology, and RT dose are summarized in Table 2. The median follow-up was 57.2
Discussion
The ability to accurately assess prognosis is critical to appropriately assess and individualize treatment recommendations for patients with spinal metastases. Despite the importance of prognostication in patients in this setting, there are few clinical tools in use that accurately and reliably predict survival in patients undergoing palliative RT for metastatic disease to the spine. Our study sought to utilize the independently validated NESMS prognostication model established by Ghori et al.
Conclusions
Predicting survival outcomes after RT alone for metastatic disease of the spine is a challenge important for guiding radiation treatment decisions. The recently introduced NESMS is a tool used to predict 1-year survival following surgery for spinal metastases and has been validated in independent cohorts of surgical patients. There are limited data on the development of new prognostication schemes or the applicability of existing schemes to patients with spinal metastases treated with RT alone,
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FDA device/drug status: Not applicable.
Author disclosures: DDS: Nothing to disclose. YHC: Nothing to disclose. TCL: Nothing to disclose. DL: Nothing to disclose. TAB: Nothing to disclose. AS: Nothing to disclose. SS: Nothing to disclose. DNC: Nothing to disclose. JHC: Nothing to disclose. CHC: Nothing to disclose. MH: Nothing to disclose. MLF: Nothing to disclose. LMH: Nothing to disclose.
The disclosure key can be found on the Table of Contents and at www.TheSpineJournalOnline.com.