title: Diaphyseal osteosarcomas have distinct clinical features from metaphyseal osteosarcomas.
abstract: OBJECTIVE
  The aim of this study was to clarify the clinical features and outcomes of diaphyseal osteosarcoma.
  
  
  METHODS
  Patients with newly-diagnosed high-grade osteosarcoma occurring in the long bone were eligible for this retrospective study. Clinicopathological information was collected from our database and compared with 36 diaphyseal, 405 proximal and 519 distal metaphyseal, and 14 whole bone osteosarcoma patients. Additionally, case-control study matching by age, gender, site, and metastatic status at diagnosis with 1:3 ratio of 36 diaphyseal to 108 metaphyseal osteosarcomas patients was also conducted.
  
  
  RESULTS
  Five-year overall survival and metastasis-free survival of the three groups including diaphyseal, metaphyseal, and whole bone osteosarcoma patients showed significant difference (P = .029 and P = .013, respectively), although there is no difference for the survivals between proximal and distal metaphyseal osteosarcoma patients. Case-control study showed that patients with diaphyseal osteosarcomas had a significantly larger tumour (mean 13.5 cm vs 10 cm, P = .026), and demonstrated higher pathologic fracture rate (28% vs 12%, P = .033), superior 5-year metastasis-free survival (74% vs 40%, P = .0068), and slightly better 5-year overall survival (68% vs 46%, P = .074). Prognostic factor analysis showed that a pathologic fracture significantly decreased the survival of the patients with diaphyseal osteosarcoma.
  
  
  CONCLUSIONS
  The current study showed that diaphyseal osteosarcoma has distinct clinical features from metaphyseal osteosarcoma having an increased risk of pathologic fractures but with favorable survival outcome.
authors.affiliation: Oncology Unit, Royal Orthopaedic Hospital, Bristol Road South, Northfield, Birmingham B31 2AP, United Kingdom. Electronic address: siwata@chiba-cc.jp.
authors.forename: S
authors.initials: S
authors.lastname: Iwata
authors.affiliation: Oncology Unit, Royal Orthopaedic Hospital, Bristol Road South, Northfield, Birmingham B31 2AP, United Kingdom. Electronic address: tomoki66@clin.medic.mie-u.ac.jp.
authors.forename: T
authors.initials: T
authors.lastname: Nakamura
authors.affiliation: Oncology Unit, Royal Orthopaedic Hospital, Bristol Road South, Northfield, Birmingham B31 2AP, United Kingdom. Electronic address: louie.gaston@nhs.net.
authors.forename: C L
authors.initials: CL
authors.lastname: Gaston
authors.affiliation: Oncology Unit, Royal Orthopaedic Hospital, Bristol Road South, Northfield, Birmingham B31 2AP, United Kingdom. Electronic address: simon.carter5@nhs.net.
authors.forename: S R
authors.initials: SR
authors.lastname: Carter
authors.affiliation: Oncology Unit, Royal Orthopaedic Hospital, Bristol Road South, Northfield, Birmingham B31 2AP, United Kingdom. Electronic address: roger.tillman@nhs.net.
authors.forename: R M
authors.initials: RM
authors.lastname: Tillman
authors.affiliation: Oncology Unit, Royal Orthopaedic Hospital, Bristol Road South, Northfield, Birmingham B31 2AP, United Kingdom. Electronic address: seggy.abudu@nhs.net.
authors.forename: A
authors.initials: A
authors.lastname: Abudu
authors.affiliation: Oncology Unit, Royal Orthopaedic Hospital, Bristol Road South, Northfield, Birmingham B31 2AP, United Kingdom. Electronic address: lee.jeys@nhs.net.
authors.forename: L
authors.initials: L
authors.lastname: Jeys
authors.affiliation: Oncology Unit, Royal Orthopaedic Hospital, Bristol Road South, Northfield, Birmingham B31 2AP, United Kingdom. Electronic address: robert.grimer@nhs.net.
authors.forename: R J
authors.initials: RJ
authors.lastname: Grimer
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000671:Amputation, Surgical; D000970:Antineoplastic Agents; D001859:Bone Neoplasms / Q000150:complications / Q000473:pathology* / Q000628:therapy; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D018483:Diaphyses / Q000473:pathology*; D018572:Disease-Free Survival; D005260:Female; D005266:Femoral Neoplasms / Q000150:complications / Q000473:pathology / Q000628:therapy; D005360:Fibula / Q000473:pathology; D005598:Fractures, Spontaneous / Q000209:etiology; D006801:Humans; D006811:Humerus / Q000473:pathology; D008297:Male; D008875:Middle Aged; D012516:Osteosarcoma / Q000150:complications / Q000473:pathology* / Q000628:therapy; D011379:Prognosis; D011878:Radiotherapy; D011884:Radius / Q000473:pathology; D012189:Retrospective Studies; D013977:Tibia / Q000473:pathology; D016896:Treatment Outcome; D014457:Ulna / Q000473:pathology; D055815:Young Adult
chemical_list: D000970:Antineoplastic Agents
keywords: Case–control study; Diaphysis; Metaphysis; Osteosarcoma; Pathologic fracture