title: Prognostic effect of diaphyseal location in osteosarcoma: a cohort case-control study at a single institute.
abstract: BACKGROUND
  Little is known about the clinical outcome or prognosis of diaphyseal osteosarcoma treated with modern therapeutic strategies.
  
  
  METHODS
  We conducted both cohort (n=400) and case-control (n=102) studies on 34 American Joint Committee on Cancer stage II diaphyseal osteosarcomas of the extremities.
  
  
  RESULTS
  In the cohort study, 34 patients with a diaphyseal osteosarcoma showed significantly better survival than 366 patients with metaphyseal osteosarcoma (5-year metastasis-free survival rates, 87% for cases vs. 59% for controls, P=0.01; 5-year overall survival rates, 90% for cases vs. 71% for controls, P=0.04). The case-control study conducted on 34 patients with diaphyseal osteosarcoma and 68 controls (recruited from among the 366 patients with metaphyseal osteosarcoma by matching for age, tumor volume, and location) showed no survival difference between cases and controls (5-year metastasis- free survival rates, P=0.07; 5-year overall survival rates, P=0.26).
  
  
  CONCLUSIONS
  Location differences between the diaphysis and metaphysis may have no prognostic relevance.
authors.affiliation: Department of Orthopedic Surgery, Korea Cancer Center Hospital, Seoul, Korea.
authors.forename: Chang-Bae
authors.initials: CB
authors.lastname: Kong
authors.forename: Min Suk
authors.initials: MS
authors.lastname: Kim
authors.forename: Soo-Yong
authors.initials: SY
authors.lastname: Lee
authors.forename: Wan Hyeong
authors.initials: WH
authors.lastname: Cho
authors.forename: Won Seok
authors.initials: WS
authors.lastname: Song
authors.forename: Jun Ah
authors.initials: JA
authors.lastname: Lee
authors.forename: Ji Young
authors.initials: JY
authors.lastname: Yoo
authors.forename: So Hak
authors.initials: SH
authors.lastname: Chung
authors.forename: Dae-Geun
authors.initials: DG
authors.lastname: Jeon
mesh_terms: D000293:Adolescent; D000328:Adult; D001859:Bone Neoplasms / Q000473:pathology* / Q000628:therapy; D016022:Case-Control Studies; D015331:Cohort Studies; D018483:Diaphyses / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D009367:Neoplasm Staging; D012516:Osteosarcoma / Q000473:pathology* / Q000628:therapy; D011379:Prognosis; D012189:Retrospective Studies; D015996:Survival Rate; D016896:Treatment Outcome; D055815:Young Adult