title: Measuring treatment response to systemic therapy and predicting outcome in biliary tract cancer: comparing tumor size, volume, density, and metabolism.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the response of biliary tract cancer treated with multidrug chemotherapy using FDG PET in comparison with morphologic and density changes.
  
  
  METHODS
  In this phase II clinical trial, 28 patients with unresectable or metastatic biliary tract cancers treated with gemcitabine and oxaliplatin combined with bevacizumab (GEMOX-B) underwent FDG PET and contrast-enhanced CT at baseline and after the second cycle of the therapy (8 weeks). A single reviewer recorded tumor maximum standardized uptake value (SUVmax) along with size, volume (3D-sphere), and density. The percentage changes of the parameters were compared with progression-free survival at 7 months. Overall survival was compared with the percentage change of SUVmax.
  
  
  RESULTS
  After 8 weeks, measurable reductions (±SD) in size (7.05±4.19 to 5.52±3.28 cm, -21.70%), volume (411.38±540.08 to 212.41±293.45 cm3, -48.36%), and density (60.76±20.65 to 50.68±16.89 HU, -15.59%) were noted along with a substantial drop in SUVmax (5.95±1.95 to 3.36±1.28, -43.52%). The SUVmax change showed positive correlations with tumor size change (R2=0.39, p=0.0004) and volumetric change (R2=0.34, p=0.001). Patients who showed a larger drop in SUVmax at 8 weeks correlated with favorable progression-free survival (p=0.02). ROC analysis showed that a 45% reduction in SUVmax was the best cutoff value to detect favorable progression-free survival patients. When we used this cutoff value, Kaplan-Meier analysis showed that patients with tumors showing greater reduction in SUVmax had favorable progression-free survival and overall survival (p=0.0009, p=0.03).
  
  
  CONCLUSIONS
  In biliary tract cancers treated with GEMOX-B, the reduction of SUVmax after therapy is a better predictor for survival than morphologic and density changes.
authors: 1 Department of Radiology, Division of Abdominal Imaging and Intervention, Massachusetts General Hospital, Harvard Medical School, 55 Fruit St, White 270, Boston, MA 02114.
authors: Dushyant V
authors: DV
authors: Sahani
authors: Koichi
authors: K
authors: Hayano
authors: Anna
authors: A
authors: Galluzzo
authors: Andrew X
authors: AX
authors: Zhu
mesh_terms: D061067:Antibodies, Monoclonal, Humanized / Q000008:administration & dosage; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D000068258:Bevacizumab; D001661:Biliary Tract Neoplasms / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000473:pathology; D003287:Contrast Media / Q000493:pharmacokinetics; D003841:Deoxycytidine / Q000008:administration & dosage / Q000031:analogs & derivatives; D018450:Disease Progression; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics; D006801:Humans; D008297:Male; D008875:Middle Aged; D009944:Organoplatinum Compounds / Q000008:administration & dosage; D000077150:Oxaliplatin; D049268:Positron-Emission Tomography; D011857:Radiographic Image Interpretation, Computer-Assisted; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D015996:Survival Rate; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D000093542:Gemcitabine
chemical_list: D061067:Antibodies, Monoclonal, Humanized; D003287:Contrast Media; D009944:Organoplatinum Compounds; D019275:Radiopharmaceuticals; D000077150:Oxaliplatin; D003841:Deoxycytidine; D019788:Fluorodeoxyglucose F18; D000068258:Bevacizumab; D000093542:Gemcitabine
keywords: CT; PET; RECIST; biliary tract cancer; density; tumor