title: Standardized Added Metabolic Activity Predicts Survival After Intra-arterial Resin-Based 90Y Radioembolization Therapy in Unresectable Chemorefractory Metastatic Colorectal Cancer to the Liver.
abstract: OBJECTIVE
  Standardized added metabolic (SAM) activity is a functional objective measurement of the total tumoral metabolic activity that avoids partial volume effect and thresholding, which limit conventional PET parameters. The purpose of this study is to investigate the role of SAM in predicting survival in unresectable, chemorefractory colorectal hepatic metastatic disease treated with resin-based Y radioembolization.
  
  
  METHODS
  This is a prospective correlative study of patients with unresectable, chemorefractory colorectal liver metastasis who underwent F-FDG PET/CT and CT/MRI before and after Y. Target RECIST, PERCIST, change in total glycolytic activity (ΔTGA), and ΔSAM treatment response were assessed. Percentage changes in diameter, SUVpeak, TGA, and SAM were calculated pre- and post-Y therapy and objective response was defined as >30% change (responders). Survival analysis by Kaplan-Meier, log-rank, and Cox proportional hazard models were performed and significance was set at <0.05.
  
  
  RESULTS
  Sixteen patients (mean age of 61.6) were enrolled and performed a total of 20 Y therapies. After Y, target ΔSAM showed an objective response rate of 40% vs. 35%, 30%, and 22.2% based on target ΔTGA, PERCIST, and RECIST criteria, respectively. Median overall survival (OS) of the cohort after Y was 9.2 months (CI 95% 2.2-16.2). Patients demonstrating objective response based on ΔSAM had a median OS of 22.7 months (CI 95% 12.4-33.0) vs. 6.7 (CI 95% 4.2-9.2) in non-responders (P = 0.007). On multivariate analysis, hazard ratios for the objective response group based on target ΔSAM were 0.01 (P = 0.03) vs. 0.05 (P = 0.08), 0.20 (P = 0.29), and 0.91 (P = 0.98) based on target ΔTGA, PERCIST, and RECIST criteria, respectively.
  
  
  CONCLUSIONS
  In unresectable colorectal liver metastatic disease refractory to standard chemotherapy, ΔSAM predicted OS for assessment of response following Y radioembolization therapy, whereas RECIST, PERCIST, and ΔTGA did not.
authors.affiliation: From the *Divisions of Interventional Radiology and Image Guided Medicine and †Nuclear Medicine and Molecular Imaging, Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, GA; ‡Division of Interventional Radiology, Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, CT; and §Yale Cancer Center, Yale University, New Haven, CT.
authors.forename: Faramarz
authors.initials: F
authors.lastname: Edalat
authors.forename: Juan C
authors.initials: JC
authors.lastname: Camacho
authors.forename: Nima
authors.initials: N
authors.lastname: Kokabi
authors.forename: Ayse T
authors.initials: AT
authors.lastname: Kendi
authors.forename: James R
authors.initials: JR
authors.lastname: Galt
authors.forename: Hyun S
authors.initials: HS
authors.lastname: Kim
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015179:Colorectal Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000532:radiotherapy; D004621:Embolization, Therapeutic; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008113:Liver Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy / Q000556:secondary; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals / Q000627:therapeutic use; D015021:Yttrium Radioisotopes / Q000627:therapeutic use
chemical_list: D019275:Radiopharmaceuticals; D015021:Yttrium Radioisotopes; D019788:Fluorodeoxyglucose F18