title: Evaluation of neoadjuvant therapy response of osteogenic sarcoma using FDG PET.
abstract: According to the current treatment protocol of the Cooperative Osteosarcoma Study (COSS), monitoring preoperative chemotherapy response and estimating grade of tumor regression in patients with osteosarcoma is mandatory before surgical removal of the tumor, particularly if a limb salvage procedure is intended. In addition, response to neoadjuvant chemotherapy is considered as an important prognostic indicator. The aim of this prospective study was to assess the usefulness of 2-(18F) fluoro-2-deoxy-D-glucose (FDG) PET in the noninvasive evaluation of neoadjuvant chemotherapy response in osteosarcoma.
  
  
  METHODS
  In 27 patients with osteosarcoma, we determined tumor-to-background ratios (TBRs) of FDG uptake with PET, before and after neoadjuvant chemotherapy according to COSS 86c or COSS 96 protocols, respectively. We compared changes in glucose metabolism of osteosarcomas with the histologic grade of regression in the resected specimen, according to Salzer-Kuntschik, discriminating responders (grades I-III; n = 17) and nonresponders (grades IV-VI; n = 10).
  
  
  RESULTS
  The decrease of FDG uptake in osteosarcomas expressed as a ratio of posttherapeutic and pretherapeutic TBRs showed a close correlation to the amount of tumor necrosis induced by polychemotherapy (P < 0.001; Spearman). With a TBR ratio cutoff level of 0.6, all responders and 8 of 10 nonresponders could be identified by PET. In addition, lung metastases of osteosarcoma were detected with FDG PET in 4 patients.
  
  
  CONCLUSIONS
  FDG PET provides a promising tool for noninvasive evaluation of neoadjuvant chemotherapy response in osteosarcoma. This could imply consequences for the choice of surgical strategy, because a limb salvage procedure cannot be recommended in patients nonresponsive to preoperative chemotherapy unless wide surgical margins can safely be achieved.
authors.affiliation: Department of Trauma, Hand and Reconstructive Surgery, University of Ulm, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Schulte
authors.forename: D
authors.initials: D
authors.lastname: Brecht-Krauss
authors.forename: M
authors.initials: M
authors.lastname: Werner
authors.forename: E
authors.initials: E
authors.lastname: Hartwig
authors.forename: M R
authors.initials: MR
authors.lastname: Sarkar
authors.forename: P
authors.initials: P
authors.lastname: Keppler
authors.forename: J
authors.initials: J
authors.lastname: Kotzerke
authors.forename: A
authors.initials: A
authors.lastname: Guhlmann
authors.forename: G
authors.initials: G
authors.lastname: Delling
authors.forename: S N
authors.initials: SN
authors.lastname: Reske
mesh_terms: D000293:Adolescent; D000328:Adult; D001859:Bone Neoplasms / Q000000981:diagnostic imaging* / Q000188:drug therapy / Q000601:surgery; D017024:Chemotherapy, Adjuvant; D002648:Child; D005260:Female; D005462:Fluorine Radioisotopes; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009336:Necrosis; D009367:Neoplasm Staging; D015588:Observer Variation; D012516:Osteosarcoma / Q000000981:diagnostic imaging* / Q000188:drug therapy / Q000601:surgery; D011446:Prospective Studies; D019275:Radiopharmaceuticals; D013997:Time Factors; D014055:Tomography, Emission-Computed
chemical_list: D005462:Fluorine Radioisotopes; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18