Effectiveness of Positron Emission Tomography/Computed Tomography as a Guide for Palliative Radiation Therapy for Spinal Metastases.

Abstract

As back pain is the presenting symptom in 95% of patients with epidural spinal metastases, appropriately identifying and treating the most symptomatic levels can provide significant palliation. The purpose of this study was to analyze the ability of combined positron emission tomography (PET)/computed tomography (CT) to identify spinal metastases with high metabolic activity and guide radiotherapy. We sought to correlate improvement in back pain with reduction in standard uptake value (SUV) after treatment. Retrospective review was performed of 72 patients with spinal metastases treated with stereotactic ablative radiation therapy at a single center between 2002 and 2014. PET/CT was used to calculate SUVs for spinal metastases, and treatment planning was based on PET/CT results. Preoperative and postoperative pain levels were assessed in all patients. Reduction in pain scores was found in 78% of treated patients. A significant reduction in pain was identified in patients with >5 metastases compared with fewer lesions (P < 0.05). Degree of change in SUV did not correlate significantly with pain relief. However, comparing pretreatment and posttreatment PET/CT, patients with improved pain consistently displayed decreased SUV. PET/CT was shown to be a useful adjunct in radiation treatment planning with change in SUV correlating with symptomatic improvement. This study paves the way for future prospective studies to further assess utility and cost-effectiveness of this imaging modality in radiation treatment planning for spinal metastases.