Use of PET-CT scan as tool of treatment response evaluation for solitary spine metastasis after SBRT

Abstract

OBJECTIVES: We investigated the use of FDG-PET-CT scan to evaluate treatment response after SBRT for solitary bone metastasis. METHODS: Patients with solitary bone metastasis of various underlying primary malignancies treated with SBRT were reviewed. They all had FDG-PET-CT scan immediately before SBRT and 3-4 months after SBRT to evaluate treatment response. RESULTS: Five patients (3 with lung cancers and 2 with breast cancer) fulfilled the above criteria. One patient received one course of 2-dimensional palliative radiotherapy to the affected thoracic spine before) before SBRT. 24Gy/2fr/1 week was chosen for 3 patients while 27Gy/3fr/1 week was chosen for another 2 patients according to treating oncologists’ decision. Follow-up FDG-PET-CT scan showed complete metabolic response in 4 patients (80%) and partial metabolic response (80% decrease in total lesion glycolysis) in the remaining 1 patient. No evidence of local progression was noted in all patients so far. All patients tolerated SBRT uneventfully with only grade 1 oesophagitis noted in one patient and grade 1 pneumonitis i 2 patients. CONCLUSION: FDG-PET-CT scan was found clinically useful to assess treatment response after SBRT for solitary spinal metastasis.