title: Prognostic Factors in Patients Treated with 223Ra: The Role of Skeletal Tumor Burden on Baseline 18F-Fluoride PET/CT in Predicting Overall Survival.
abstract: The purpose of this study was to evaluate outcome after (223)Ra dichloride therapy ((223)Ra) and to determine whether skeletal tumor burden on whole-body (18)F-fluoride PET/CT can be used as a predictive biomarker of survival in patients treated with (223)Ra.
  
  
  METHODS
  Forty-two patients with hormone-refractory prostate cancer underwent (223)Ra and a baseline fluoride PET/CT scan. Fluoride PET/CT parameters were generated, including maximum standardized uptake value (SUVmax) of the hottest lesion (hSUVmax), average SUV of disease (Mean10), and skeletal tumor burden indices of total fluoride skeletal metastatic lesion uptake (TLF10) and total volume of fluoride avid bone metastases (FTV10). Overall survival (OS) was the primary endpoint. Secondary endpoints were progression-free survival and skeletal-related event (SRE).
  
  
  RESULTS
  Skeletal tumor burden indices (TLF10 and FTV10) derived from fluoride PET/CT at baseline were highly correlated and significant independent predictors of OS (P = 0.0212; hazard ratio = 5.990; 95% confidence interval = 1.306-27.475). A TLF10 cutoff value of 8,000 discriminated survivors from nonsurvivors after (223)Ra (with TLF10 values < 8,000, the median OS was not estimated, whereas with TLF10 > 8,000, the median OS was 6.67 mo). Visual analysis, Mean10, and hSUVmax were not predictors of OS or progression-free survival. Mean10 was found to be a significant univariate predictor of the odds of having an SRE (P = 0.0445; odds ratio = 1.30; 95% confidence interval = 1.006-1.681), with a Mean10 greater than 19 increasing the risk of SRE.
  
  
  CONCLUSIONS
  Skeletal tumor burden on baseline fluoride PET/CT is a predictive biomarker of OS and the risk of an SRE in patients treated with (223)Ra.
authors.affiliation: Department of Nuclear Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas elba.etchebehere@gmail.com.
authors.forename: Elba C
authors.initials: EC
authors.lastname: Etchebehere
authors.affiliation: Department of Genitourinary Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas; and.
authors.forename: John C
authors.initials: JC
authors.lastname: Araujo
authors.affiliation: Department of Biostatistics, The University of Texas MD Anderson Cancer Center, Houston, Texas.
authors.forename: Patricia S
authors.initials: PS
authors.lastname: Fox
authors.affiliation: Department of Nuclear Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas.
authors.forename: Nancy M
authors.initials: NM
authors.lastname: Swanston
authors.affiliation: Department of Nuclear Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas.
authors.forename: Homer A
authors.initials: HA
authors.lastname: Macapinlac
authors.affiliation: Department of Nuclear Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas.
authors.forename: Eric M
authors.initials: EM
authors.lastname: Rohren
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000378:metabolism; D001859:Bone Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000532:radiotherapy*; D001842:Bone and Bones / Q000473:pathology; D018572:Disease-Free Survival; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging / Q000379:methods; D016017:Odds Ratio; D049268:Positron-Emission Tomography / Q000379:methods; D011379:Prognosis; D016016:Proportional Hazards Models; D064129:Prostatic Neoplasms, Castration-Resistant / Q000000981:diagnostic imaging / Q000532:radiotherapy; D011868:Radioisotopes / Q000737:chemistry*; D011883:Radium / Q000737:chemistry*; D015203:Reproducibility of Results; D012107:Research Design; D014057:Tomography, X-Ray Computed / Q000379:methods; D016896:Treatment Outcome
chemical_list: D014408:Biomarkers, Tumor; D011868:Radioisotopes; D019788:Fluorodeoxyglucose F18; D011883:Radium
keywords: 223Ra; NaF PET/CT; fluoride PET/CT; prostate cancer; skeletal tumor burden