title: Extraskeletal osteosarcoma in Norway, between 1975 and 2009, and a brief review of the literature.
abstract: OBJECTIVE
  To evaluate the clinicopathological features of extraskeletal osteosarcoma (ESOS) and its response to multimodal therapy.
  
  
  METHODS
  A nationwide cohort comprising all Norwegian histologically verified ESOS patients between 1975 and 2009 supplemented with clinical reports from all hospitals involved in sarcoma management.
  
  
  RESULTS
  Thirty-seven patients were classified as ESOS, mostly elderly people. Seventy-six % had an axial tumour, including nine patients with radiation-induced ESOS. The gender balance was equal. The 5-year sarcoma-specific survival (SSS) was 16 %. Adequate surgical remission had a positive impact on SSS, in contrast to chemotherapy and radiotherapy. Primary metastatic disease, elevated tumour size and elevated serum alkaline phosphatase, serum lactate dehydrogenase and Ki67, respectively, all predicted poor outcome.
  
  
  CONCLUSIONS
  The relatively poor prognosis of ESOS may relate to both primary chemotherapy resistance and different biologic characteristics of these tumours as compared to conventional osteosarcoma. Hence, new predictive molecular markers and therapeutic approaches for treatment of ESOS are needed.
authors: Department of Oncology, Oslo University Hospital, Norwegian Radium Hospital, Oslo, Norway The Norwegian Cancer Registry, Oslo, Norway kjetil.berner@ous-hf.no.
authors: Kjetil
authors: K
authors: Berner
authors: Department of Pathology, Oslo University Hospital, Norwegian Radium Hospital, Oslo, Norway.
authors: Bodil
authors: B
authors: Bjerkehagen
authors: Department of Oncology, Oslo University Hospital, Norwegian Radium Hospital, Oslo, Norway Institute of Clinical Medicine, University of Oslo, Oslo, Norway.
authors: Øyvind S
authors: ØS
authors: Bruland
authors: Department of Pathology, Oslo University Hospital, Norwegian Radium Hospital, Oslo, Norway Institute of Clinical Medicine, University of Oslo, Oslo, Norway.
authors: Aasmund
authors: A
authors: Berner
mesh_terms: D000368:Aged; D001859:Bone Neoplasms / Q000453:epidemiology / Q000473:pathology / Q000628:therapy*; D049109:Cell Proliferation / Q000235:genetics; D003131:Combined Modality Therapy; D058750:Epithelial-Mesenchymal Transition / Q000235:genetics; D005260:Female; D006801:Humans; D008297:Male; D009664:Norway; D012516:Osteosarcoma / Q000453:epidemiology / Q000235:genetics / Q000473:pathology / Q000628:therapy*; D011379:Prognosis; D016896:Treatment Outcome
keywords: extraskeletal; immunohistochemistry; osteosarcoma; therapy; treatment outcome