title: High-grade osteosarcoma of the extremity: differences between localized and metastatic tumors at presentation.
abstract: BACKGROUND
  In osteosarcoma, as in other tumors, the presence of metastases at presentation is generally considered a consequence of late diagnosis. To verify this, the authors investigated whether there was a relationship between the stage of the disease at presentation and several clinical and pathologic characteristics, including the interval between the onset of first symptoms or signs and the final diagnosis.
  
  
  METHODS
  One thousand seventy-one patients with high-grade osteosarcoma of the extremity were observed between 1980 and 1999. Of these, 891 had a localized tumor and 180 had metastases at the time of diagnosis.
  
  
  RESULTS
  Compared with patients with localized disease, patients with detectable metastases at the time of diagnosis had higher serum levels of alkaline phosphatase, larger primary lesions, and tumors often located in the femur and humerus. In terms of time to diagnosis, the interval between the onset of first symptoms and the final diagnosis was significantly shorter in patients with metastases than in patients with localized tumor. This surprising finding probably reflects a more rapid growth of the tumor.
  
  
  CONCLUSIONS
  These results suggest a different biologic phenotype and aggressiveness of the tumor in a subgroup of patients and that the stage of the disease at presentation depends more on the properties of these tumors than on late diagnosis.
authors.affiliation: Department of Chemotherapy, Rizzoli Orthopedic Institute, Bologna, Italy. gaetano.bacci@ior.it
authors.forename: Gaetano
authors.initials: G
authors.lastname: Bacci
authors.forename: Stefano
authors.initials: S
authors.lastname: Ferrari
authors.forename: Alessandra
authors.initials: A
authors.lastname: Longhi
authors.forename: Cristiana
authors.initials: C
authors.lastname: Forni
authors.forename: Marcello
authors.initials: M
authors.lastname: Zavatta
authors.forename: Michela
authors.initials: M
authors.lastname: Versari
authors.forename: Keith
authors.initials: K
authors.lastname: Smith
mesh_terms: D000293:Adolescent; D000328:Adult; D001859:Bone Neoplasms / Q000145:classification / Q000473:pathology*; D005260:Female; D005266:Femoral Neoplasms / Q000473:pathology; D006801:Humans; D007558:Italy; D008297:Male; D009362:Neoplasm Metastasis; D012516:Osteosarcoma / Q000145:classification / Q000473:pathology*; D012189:Retrospective Studies