title: Reduction of glucose metabolic activity is more accurate than change in size at predicting histopathologic response to neoadjuvant therapy in high-grade soft-tissue sarcomas.
abstract: OBJECTIVE
  Change in tumor size as classified by Response Evaluation Criteria in Solid Tumors poorly correlates with histopathologic response to neoadjuvant therapy in patients with soft-tissue sarcomas. The aim of this study was to prospectively evaluate whether positron emission tomography with (18)F-fluorodeoxyglucose (FDG-PET) allows for a more accurate evaluation of histopathologic response.
  
  
  METHODS
  From January 2005 to January 2007, 42 patients with resectable biopsy-proven high-grade soft-tissue sarcoma underwent a FDG-PET/computed tomography scan before and after neoadjuvant treatment. Relative changes in tumor FDG uptake and size from the baseline to the follow-up scan were calculated, and their accuracy for assessment of histopathologic response was compared by receiver operating characteristic curve analysis. Histopathologic response was defined as > or =95% tumor necrosis.
  
  
  RESULTS
  In histopathologic responders (n = 8; 19%), reduction in tumor FDG uptake was significantly greater than in nonresponders (P < 0.001), whereas no significant differences were found for tumor size (P = 0.24). The area under the receiver operating characteristic curve for metabolic changes was 0.93, but only 0.60 for size changes (P = 0.004). Using a 60% decrease in tumor FDG uptake as a threshold resulted in a sensitivity of 100% and a specificity of 71% for assessment of histopathologic response, whereas Response Evaluation Criteria in Solid Tumors showed a sensitivity of 25% and a specificity of 100%.
  
  
  CONCLUSIONS
  Quantitative FDG-PET was significantly more accurate than size-based criteria at assessing histopathologic response to neoadjuvant therapy. FDG-PET should be considered as a modality to monitor treatment response in patients with high-grade soft-tissue sarcoma.
authors.affiliation: Abteilung Nuklearmedizin (University of Freiburg), Freiburg, Germany.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Evilevitch
authors.forename: Wolfgang A
authors.initials: WA
authors.lastname: Weber
authors.forename: William D
authors.initials: WD
authors.lastname: Tap
authors.forename: Martin
authors.initials: M
authors.lastname: Allen-Auerbach
authors.forename: Kira
authors.initials: K
authors.lastname: Chow
authors.forename: Scott D
authors.initials: SD
authors.lastname: Nelson
authors.forename: Fredrick R
authors.initials: FR
authors.lastname: Eilber
authors.forename: Jeffery J
authors.initials: JJ
authors.lastname: Eckardt
authors.forename: Robert M
authors.initials: RM
authors.lastname: Elashoff
authors.forename: Michael E
authors.initials: ME
authors.lastname: Phelps
authors.forename: Johannes
authors.initials: J
authors.lastname: Czernin
authors.forename: Fritz C
authors.initials: FC
authors.lastname: Eilber
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000627:therapeutic use; D003131:Combined Modality Therapy; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics*; D006801:Humans; D007890:Leiomyosarcoma / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D008080:Liposarcoma / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D012509:Sarcoma / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology* / Q000532:radiotherapy; D014057:Tomography, X-Ray Computed
chemical_list: D000970:Antineoplastic Agents; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18