title: FDG PET uptake as a predictor of pain response in palliative radiation therapy in patients with bone metastasis.
abstract: OBJECTIVE
  To evaluate the relationship between fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET) maximum standardized uptake value (SUV(max)) and pain response to radiation therapy (RT) in patients with bone metastasis.
  
  
  METHODS
  Institutional ethical board approval for the study was obtained, with informed consent, for this prospective study. Thirty-one patients with metastatic bone pain who underwent FDG PET/computed tomography before RT were included. Patients were diagnosed with lung (n = 16), breast (n = 7), stomach (n = 2), and head and neck cancers (n = 3), as well as unknown primary tumor (n = 3). Eighty-five painful metastatic locations with FDG PET scans geographically corresponding to 40 treatment fields were evaluated. Pain scores using visual analog scale or faces pain rating scale and SUV(max) at each location were recorded. All patients were treated with a single fraction 8 Gy RT. Pain scores after RT were assessed at weeks 2, 4, 8, 12, 16, 20, and 24. The pretreatment pain scores and pain response to RT were compared with FDG PET SUV(max) of each location. Pearson correlation, independent t test, one-way analysis of variance, and χ(2) tests were used for statistical analysis.
  
  
  RESULTS
  Median SUV(max) and initial pain scores for all locations were 7.2 (range, 1.5-22.5) and 6 (range, 2-8), respectively. Median follow-up time was 24 (range, 3-112) weeks. Median SUV(max) was 4.5 (range, 3.1-7.3), 4.75 (range, 1.5-10.3), 8.8 (range, 5.2-11.9), and 12.1 (range, 7-22.5) for pretreatment pain scores of 2, 4, 6, and 8, respectively. SUV(max) was correlated with pretreatment pain scores (P < .0001). SUV(max) and pretreatment pain scores were also significantly associated with pain response to RT. Median SUV(max) for locations with complete response, partial response, pain progression, and indeterminate response was 5.2, 9.75, 10.8, and 6.4, respectively (P ≤ .001).
  
  
  CONCLUSIONS
  FDG PET SUV(max) correlated with initial pain severity and pain response to RT and can be used as a predictive factor for treatment response in patients with painful bone metastasis treated with palliative RT.
authors.affiliation: From the Departments of Radiation Oncology (M.A., A.K., H.E., F.A.) and Nuclear Medicine (M.Y.), Gaziantep University Medical School, Gaziantep, Turkey.
authors.forename: Mustafa
authors.initials: M
authors.lastname: Adli
authors.forename: Abdurrahman
authors.initials: A
authors.lastname: Kuzhan
authors.forename: Hilal
authors.initials: H
authors.lastname: Alkis
authors.forename: Fundagul
authors.initials: F
authors.lastname: Andic
authors.forename: Mustafa
authors.initials: M
authors.lastname: Yilmaz
mesh_terms: D000328:Adult; D000368:Aged; D001859:Bone Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy* / Q000556:secondary; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D010147:Pain Measurement; D010148:Intractable Pain / Q000000981:diagnostic imaging*; D010166:Palliative Care; D049268:Positron-Emission Tomography / Q000379:methods*; D011446:Prospective Studies; D019275:Radiopharmaceuticals; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18