title: Evaluation of metabolic response with18F-FDG PET-CT in patients with advanced or recurrent thymic epithelial tumors.
abstract: BACKGROUND
  Patients with advanced or recurrent thymic epithelial tumors (TETs) often need several consecutive lines of chemotherapy. The aim of this retrospective monocentric study was to test whether18F-Fluorodeoxyglucose positron emission tomography-computed tomography (18F-FDG PET-CT) is able to monitor standard chemotherapy efficacy in those patients and whether metabolic response correlates with morphovolumetric response as assessed by Response Evaluation Criteria in Solid Tumor (RECIST).
  
  
  METHODS
  We evaluated 27 consecutive patients with advanced (16 patients) or recurrent (11 patients) TETs. All patients underwent18F-FDG PET-CT before and after at least 3 cycles of chemotherapy. Maximum standardized uptake value (SUVmax) of all detected lesions was recorded and the most18F-FDG avid lesion in each patient was selected for determination of percentage change of SUVmax(ΔSUVmax) in pre- and post-treatment scans. Tumor response was assessed by contrast-enhanced computed tomography (CE-CT) using RECIST criteria. Receiver operating characteristic (ROC) curve analysis was performed to define the optimal threshold of ΔSUVmaxdiscriminating responders from non-responders.
  
  
  RESULTS
  Metabolic response expressed as ΔSUVmaxwas significantly correlated with morphovolumetric response (Spearman's rank correlation, r = 0.64, p = 0.001). ROC curve analysis showed that a ΔSUVmaxvalue of -25% could discriminate responders from non-responders with a sensitivity of 88% and a specificity of 80%. Conversely, basal SUVmaxvalues were not predictive of morphovolumetric tumor response.
  
  
  CONCLUSIONS
  Our findings indicate that metabolic response assessed by18F-FDG PET-CT, through evaluation of ΔSUVmax, may allow identification of responders and non-responders thus guiding adaptation of therapy in patients with advanced or recurrent TETs.
authors.affiliation: Department of Advanced Biomedical Sciences, University of Naples Federico II, Via Pansini 5, Edificio 10, 80131, Naples, Italy.
authors.forename: Sabrina
authors.initials: S
authors.lastname: Segreto
authors.affiliation: Institute of Biostructures and Bioimaging, National Research Council, Via T. De Amicis 95, 80145, Naples, Italy.
authors.forename: Rosa
authors.initials: R
authors.lastname: Fonti
authors.affiliation: Rare Tumors Reference Center, University of Naples Federico II, Via S. Pansini 5, 80131, Naples, Italy.
authors.forename: Margaret
authors.initials: M
authors.lastname: Ottaviano
authors.affiliation: Department of Advanced Biomedical Sciences, University of Naples Federico II, Via Pansini 5, Edificio 10, 80131, Naples, Italy.
authors.forename: Sara
authors.initials: S
authors.lastname: Pellegrino
authors.affiliation: Department of Medicine and Surgery, University of Salerno, Via S. Allende, 84081, Baronissi, Salerno, Italy.
authors.forename: Leonardo
authors.initials: L
authors.lastname: Pace
authors.affiliation: Rare Tumors Reference Center, University of Naples Federico II, Via S. Pansini 5, 80131, Naples, Italy.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Damiano
authors.affiliation: Rare Tumors Reference Center, University of Naples Federico II, Via S. Pansini 5, 80131, Naples, Italy.
authors.forename: Giovannella
authors.initials: G
authors.lastname: Palmieri
authors.affiliation: Department of Advanced Biomedical Sciences, University of Naples Federico II, Via Pansini 5, Edificio 10, 80131, Naples, Italy. delvecc@unina.it.|Institute of Biostructures and Bioimaging, National Research Council, Via T. De Amicis 95, 80145, Naples, Italy. delvecc@unina.it.
authors.forename: Silvana
authors.initials: S
authors.lastname: Del Vecchio
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000008:administration & dosage*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009375:Neoplasms, Glandular and Epithelial / Q000000981:diagnostic imaging* / Q000188:drug therapy; D000072078:Positron Emission Tomography Computed Tomography / Q000379:methods*; D012372:ROC Curve; D019275:Radiopharmaceuticals / Q000008:administration & dosage*; D012189:Retrospective Studies; D013953:Thymus Neoplasms / Q000000981:diagnostic imaging* / Q000188:drug therapy; D014057:Tomography, X-Ray Computed / Q000379:methods*; D016896:Treatment Outcome
chemical_list: D000970:Antineoplastic Agents; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
keywords: 18F-FDG PET-CT; RECIST; Thymic carcinoma; Thymoma; Tumor response