title: Response to chemotherapy estimates by FDG PET is an important prognostic factor in patients with Ewing sarcoma.
abstract: BACKGROUND
  Response to chemotherapy is a prognostic factor in patients with Ewing sarcoma (ES); the role of FDG PET to predict response in these patients has not been thoroughly investigated. We evaluated the diagnostic accuracy and the potential of FDG PET to predict response to chemotherapy (CHT).
  
  
  METHODS
  We analyzed data of 50 patients with ES (median age 12.6 years). All patients were treated with neoadjuvant CHT, and underwent surgery for local control. All patients had (18)F-FDG PET/CT at diagnosis and after induction CHT, prior to local control. We compared response assessed by histopathology with FDG PET using standard uptake values (SUVs).
  
  
  RESULTS
  Median SUV at diagnosis (SUV I) was 5 (range 1.2-17), and median SUV after neoadjuvant chemotherapy (SUV II) was 1.8 (range 0-8.4). Median SUV II/I ratio was 0.3 (range 0-1). SUV at diagnosis was significantly lower in patients with good histological response than in patients with poor histological response (median 3.8 vs. 7.2, p 0.02). We found a significant correlation between SUV II and outcome; the positive predictive value of an SUV II ≤ 2.5 for favorable response was 84.21 %, and the median SUV II was significantly higher in patients with disease progression (2.3 vs. 1.6, p = 0.04). In multivariate analysis, necrosis and SUV II were significant predictors of outcome.
  
  
  CONCLUSIONS
  (18)F-FDG PET demonstrates high diagnostic accuracy for response to initial chemotherapy in patients with ES and it correlates with outcome. The role of FDG PET in predicting response and outcome should be further investigated.
authors.affiliation: Department of Surgical Oncology for Children and Youth, Institute of Mother and Child, Ul. Kasprzaka 17a, 01-211, Warsaw, Poland. anna.raciborska@hoga.pl.
authors.forename: A
authors.initials: A
authors.lastname: Raciborska
authors.affiliation: Department of Surgical Oncology for Children and Youth, Institute of Mother and Child, Ul. Kasprzaka 17a, 01-211, Warsaw, Poland.
authors.forename: K
authors.initials: K
authors.lastname: Bilska
authors.affiliation: Department of Pediatric Hematology, Oncology and Transplant, Medical University of Lublin, Lublin, Poland.
authors.forename: K
authors.initials: K
authors.lastname: Drabko
authors.affiliation: Department of Pathology, Institute of Mother and Child, Warsaw, Poland.
authors.forename: E
authors.initials: E
authors.lastname: Michalak
authors.affiliation: Department and Clinic of Pediatric Oncology, Hematology and Bone Marrow Transplantation, Wroclaw Medical University, Wroclaw, Poland.
authors.forename: R
authors.initials: R
authors.lastname: Chaber
authors.affiliation: Department of Pediatric Hematology and Oncology Collegium Medicum, Nicolaus Copernicus University, Bydgoszcz, Poland.
authors.forename: M
authors.initials: M
authors.lastname: Pogorzała
authors.affiliation: Department of Pediatric Hematology and Oncology, Medical University of Gdansk, Gdansk, Poland.
authors.forename: K
authors.initials: K
authors.lastname: Połczyńska
authors.affiliation: Unit of Pediatric Oncology, Hematology and Chemotherapy, Medical University of Silesia, Katowice, Poland.
authors.forename: G
authors.initials: G
authors.lastname: Sobol
authors.affiliation: Department of Pediatrics and Oncology, Pediatric and Oncological Children's Centre, Chorzow, Poland.
authors.forename: M
authors.initials: M
authors.lastname: Wieczorek
authors.affiliation: Department of Pediatric Oncology and Hematology, Medical University of Bialystok Children's, Clinical Hospital of L. Zamenhof, Bialystok, Poland.
authors.forename: K
authors.initials: K
authors.lastname: Muszyńska-Rosłan
authors.affiliation: Department of Surgical Oncology for Children and Youth, Institute of Mother and Child, Ul. Kasprzaka 17a, 01-211, Warsaw, Poland.
authors.forename: M
authors.initials: M
authors.lastname: Rychlowska-Pruszyńska
authors.affiliation: Pediatric Oncology, Dana-Farber/Boston Children's Cancer and Blood Disorders Center, Harvard Medical School, Boston, MA, USA.
authors.forename: C
authors.initials: C
authors.lastname: Rodriguez-Galindo
authors.affiliation: Nuclear Medicine Department, Military Institute of Medicine, PET-CT Department, Mazovian Medical Centre, Warsaw, Poland.
authors.forename: M
authors.initials: M
authors.lastname: Dziuk
mesh_terms: D000293:Adolescent; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D001859:Bone Neoplasms / Q000000981:diagnostic imaging* / Q000188:drug therapy / Q000473:pathology; D002648:Child; D002675:Child, Preschool; D018450:Disease Progression; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D064847:Multimodal Imaging; D049268:Positron-Emission Tomography / Q000379:methods*; D011379:Prognosis; D016016:Proportional Hazards Models; D019275:Radiopharmaceuticals; D012189:Retrospective Studies; D012512:Sarcoma, Ewing / Q000000981:diagnostic imaging* / Q000188:drug therapy / Q000473:pathology; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
keywords: 18F-FDG PET; Chemotherapy; Ewing sarcoma; Necrosis