title: Extraskeletal Osteosarcoma: An International Rare Cancer Network Study.
abstract: OBJECTIVE
  To report characteristics, treatment, and outcomes for an international cohort of patients with extraskeletal osteosarcoma (ESOS).
  
  
  METHODS
  Through the Rare Cancer Network, retrospective data on patients with ESOS were collected. Patient characteristics, multimodality treatment information, and survival status were analyzed.
  
  
  RESULTS
  Thirty-seven patients in 4 health care institutions were identified. Thirty-one (86%) patients had grade 3 or 4 tumors. Most patients (27 [73%]) had stage III disease. Fourteen (38%) received neoadjuvant chemotherapy or chemoradiation. Of 28 (85%) who underwent surgery, 21 (75%) had free margins achieved and 15 (41%) subsequently received adjuvant chemotherapy. At median follow-up of 45 months, 20 (55%) patients were alive, 13 (43%) of whom were disease free. Univariate analysis showed that poor overall survival was related to stage IV (P<0.001), no surgery (P<0.001), primary size >10 cm (P=0.002), and age (P=0.002). In multivariate analysis, primary size >10 cm (P=0.005) was prognostic for overall survival. For patients without metastases, univariate analysis showed disease-free survival (DFS) related to primary size >10 cm (P=0.003), surgery (P=0.004), local recurrence (P=0.003), and age (P<0.001). In multivariate analysis for DFS, primary size >10 cm (P=0.01) and older age (P<0.001) were significant for worse outcome.
  
  
  CONCLUSIONS
  Multimodality treatment remains standard for localized ESOS, with indications for neoadjuvant therapy less clear. Larger tumor size and older age were prognostic of poorer DFS.
authors.affiliation: *Department of Radiation Oncology, Mayo Clinic §Division of Biomedical Statistics and Informatics, Mayo Clinic, Rochester, MN †Department of Radiation Oncology, Jules Bordet Institute, Brussels, Belgium ‡Department of Radiation Oncology, Cancer Center Antoine-Lacassagne, Nice, France ∥Department of Oncology, Rambam Health Care Campus, Haifa, Israel.
authors.forename: Terence T
authors.initials: TT
authors.lastname: Sio
authors.forename: Charles C
authors.initials: CC
authors.lastname: Vu
authors.forename: Schoeb
authors.initials: S
authors.lastname: Sohawon
authors.forename: Paul
authors.initials: P
authors.lastname: Van Houtte
authors.forename: Juliette
authors.initials: J
authors.lastname: Thariat
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Novotny
authors.forename: Robert C
authors.initials: RC
authors.lastname: Miller
authors.forename: Gil
authors.initials: G
authors.lastname: Bar-Sela
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D059248:Chemoradiotherapy; D017024:Chemotherapy, Adjuvant; D002945:Cisplatin / Q000008:administration & dosage; D015331:Cohort Studies; D003841:Deoxycytidine / Q000008:administration & dosage / Q000031:analogs & derivatives; D018572:Disease-Free Survival; D004317:Doxorubicin / Q000008:administration & dosage; D005047:Etoposide / Q000008:administration & dosage; D005260:Female; D006801:Humans; D007069:Ifosfamide / Q000008:administration & dosage; D035002:Lower Extremity / Q000473:pathology* / Q000601:surgery; D008297:Male; D008727:Methotrexate / Q000008:administration & dosage; D008875:Middle Aged; D016685:Mitomycin / Q000008:administration & dosage; D015999:Multivariate Analysis; D020360:Neoadjuvant Therapy; D060787:Neoplasm Grading; D009367:Neoplasm Staging; D012516:Osteosarcoma / Q000401:mortality / Q000473:pathology* / Q000628:therapy; D010386:Pelvic Neoplasms / Q000401:mortality / Q000473:pathology* / Q000628:therapy; D011379:Prognosis; D011878:Radiotherapy; D035583:Rare Diseases / Q000401:mortality / Q000473:pathology* / Q000628:therapy; D012186:Retroperitoneal Neoplasms / Q000401:mortality / Q000473:pathology* / Q000628:therapy; D012189:Retrospective Studies; D012983:Soft Tissue Neoplasms / Q000401:mortality / Q000473:pathology* / Q000628:therapy; D047368:Tumor Burden; D055815:Young Adult; D000093542:Gemcitabine
chemical_list: D003841:Deoxycytidine; D016685:Mitomycin; D005047:Etoposide; D004317:Doxorubicin; D002945:Cisplatin; D007069:Ifosfamide; D008727:Methotrexate; D000093542:Gemcitabine