title: Osteosarcomas of the mandible: multidisciplinary management of a rare tumor of the young adult a cooperative study of the GSF-GETO, Rare Cancer Network, GETTEC/REFCOR and SFCE.
abstract: BACKGROUND
  Mandibular osteosarcomas (MOS) mostly affect young adults. Their treatment is extrapolated from that of extragnathic osteosarcomas.
  
  
  METHODS
  A retrospective multicooperative group study was conducted to determine the impact of chemotherapy, adjuvant radiation therapy and surgery on outcomes and to identify prognostic factors. This ethical committee-approved study included a centralized review of histology slides and operative reports.
  
  
  RESULTS
  Of 111 patients, 58.6% were male, median age 35 years (13%, ≤18 years). Histology was osteoblastic, chondroblastic, fibroblastic, conventional not otherwise specified and others in 39.6%, 30.6%, 8.1%, 12.6% and 8.0%, respectively. Pathological World Health Organisation grades were low, intermediate and high grade in 6.4%, 11.8% and 81.8%, respectively. Surgery was carried out for 94.5% of patients. Neoadjuvant chemotherapy (mixed protocols) was carried out in 93.1% of patients. Postoperative chemotherapy and radiotherapy were carried out in 54.7% and 23.8%, respectively. Median follow-up was 59.6 months (range). Five-year local control, metastasis-free, disease-free and overall survival rates were 64.6%, 68.9%, 53.2% and 69.2%, respectively. Survival was significantly associated with age, tumor size and surgery. Wide surgery with clear margins and free flap reconstruction was the strongest prognostic factor. Neoadjuvant chemotherapy improved disease-free and metastatic-free survival and increased clear margins rates from 50% to 68%. Intermediate grades behaved like high grades in terms of metastatic-free and disease-free survival.
  
  
  CONCLUSIONS
  This homogeneous series is the largest to date and emphasizes the major impact of clear margins and multidisciplinary management. Neoadjuvant chemotherapy improves disease-free survival and should be recommended for both high and intermediate grade MOS.
authors.affiliation: Department of Radiation Oncology, Cancer Center Antoine-Lacassagne, Institut Universitaire de la Face et du Cou, University Nice Sophia-Antipolis, 06189- Nice Cedex 2, France. jthariat@hotmail.com
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mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D019468:Disease Management; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008339:Mandibular Neoplasms / Q000401:mortality / Q000473:pathology / Q000628:therapy*; D008875:Middle Aged; D015999:Multivariate Analysis; D009364:Neoplasm Recurrence, Local / Q000401:mortality / Q000517:prevention & control*; D012516:Osteosarcoma / Q000401:mortality / Q000556:secondary / Q000628:therapy*; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D016896:Treatment Outcome; D055815:Young Adult