title: Extraskeletal osteosarcoma has a favourable prognosis when treated like conventional osteosarcoma.
abstract: OBJECTIVE
  The aims of this analysis were to investigate the clinical features of extraskeletal osteosarcoma (ESOS) and examine the outcome after multi-modal therapy.
  
  
  METHODS
  The co-operative osteosarcoma study-group database was searched for patients with extraskeletal osteosarcoma. Eligible patients were included in a retrospective analysis of patient, tumour and treatment related variables and outcome. As for conventional osteosarcoma, scheduled treatment included surgery and multi-agent chemotherapy.
  
  
  RESULTS
  Seventeen eligible patients were identified with a median age of 44 years (range, 3-65 years). The thigh was the commonest tumour site. Two patients had a history of previous malignancies and two had primary metastases. Median follow-up was 3.2 years (range: 0.6-7.4 years) and at last follow-up, 11 patients were alive in complete remission, 3 patients were alive with disease and 3 patients had died of their disease. Three-year overall actuarial and event-free survival rates were 77% and 56%, respectively. Patients with macroscopically complete surgical remission had an improved overall survival (P = 0.0004).
  
  
  CONCLUSIONS
  The patients in this retrospective study had a surprisingly good survival rate. This may be due to the combination of multi-agent chemotherapy with surgery, and we recommend this approach in the treatment of ESOS.
authors.affiliation: Klinik und Poliklinik für Kinder- und Jugendmedizin, Pädiatrische Hämatologie und Onkologie, Universitätsklinikum Münster, Münster, Albert-Schweitzer-Str. 33, 48149, Germany.
authors.forename: Sing Yu
authors.initials: SY
authors.lastname: Goldstein-Jackson
authors.forename: Georg
authors.initials: G
authors.lastname: Gosheger
authors.forename: Günter
authors.initials: G
authors.lastname: Delling
authors.forename: Wolfgang E
authors.initials: WE
authors.lastname: Berdel
authors.forename: G Ulrich
authors.initials: GU
authors.lastname: Exner
authors.forename: Gernot
authors.initials: G
authors.lastname: Jundt
authors.forename: Jan-Nicolas
authors.initials: JN
authors.lastname: Machatschek
authors.forename: Andreas
authors.initials: A
authors.lastname: Zoubek
authors.forename: Heribert
authors.initials: H
authors.lastname: Jürgens
authors.forename: Stefan S
authors.initials: SS
authors.lastname: Bielack
mesh_terms: D000293:Adolescent; D000328:Adult; D001859:Bone Neoplasms / Q000175:diagnosis / Q000628:therapy; D017024:Chemotherapy, Adjuvant; D002648:Child; D002675:Child, Preschool; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012516:Osteosarcoma / Q000175:diagnosis* / Q000188:drug therapy / Q000601:surgery / Q000628:therapy*; D011379:Prognosis; D012189:Retrospective Studies; D016019:Survival Analysis