title: Oligo-Recurrence of Osteosarcoma Patients: Treatment Strategies for Pulmonary Metastases.
abstract: BACKGROUND
  Distant metastases from osteosarcoma most commonly occur in the lungs. Osteosarcoma can be cured by complete surgical resection of all metastatic lesions if the number is limited (oligo-recurrence: ≤ 5 metastatic or recurrent lesions with controlled primary lesions). This study aimed to clarify the prognostic factors for osteosarcoma patients with pulmonary metastasis and determine their oligo-recurrence status.
  
  
  METHODS
  Patients with conventional osteosarcoma who underwent definitive surgery for the primary lesion and at least one thoracotomy for pulmonary metastases were recruited to this retrospective study. Clinicopathological information was collected on each thoracotomy from 1976 to 2011, and was then analyzed statistically. We counted the number of resected nodules that were pathologically confirmed as metastatic lesions from osteosarcoma.
  
  
  RESULTS
  In total, 151 thoracotomies in 71 patients were analyzed. Forty-seven patients (66 %) underwent up to two thoracotomies, and the maximum number of thoracotomies was six. The median number of resected nodules on each thoracotomy was two, and the median total size of metastatic lesions was 20 mm. Incomplete surgical remission [relative risk (RR) 3.42], a less than 1-year interval from a previous thoracotomy (RR 1.97), more than three resected nodules (RR 2.42); and total size of more than 30 mm for pulmonary metastases (RR 2.19) were independent predictors of increased risk of tumor death by multivariate analysis.
  
  
  CONCLUSIONS
  We propose that factors contributing to oligo-recurrence of patients with pulmonary metastatic osteosarcoma include complete surgical remission, an interval from a previous thoracotomy, number of resected nodules, and total size of pulmonary metastases.
authors.affiliation: Division of Orthopedic Surgery, Chiba Cancer Center, Chiba, Japan. siwata@chiba-cc.jp.
authors.forename: Shintaro
authors.initials: S
authors.lastname: Iwata
authors.affiliation: Division of Orthopedic Surgery, Chiba Cancer Center, Chiba, Japan.
authors.forename: Tsukasa
authors.initials: T
authors.lastname: Yonemoto
authors.affiliation: Division of Thoracic Disease, Chiba Cancer Center, Chiba, Japan.
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Iizasa
authors.affiliation: Department of Radiology, Toho University Omori Medical Center, Tokyo, Japan.
authors.forename: Yuzuru
authors.initials: Y
authors.lastname: Niibe
authors.affiliation: Division of Orthopedic Surgery, Chiba Cancer Center, Chiba, Japan.
authors.forename: Hiroto
authors.initials: H
authors.lastname: Kamoda
authors.affiliation: Division of Orthopedic Surgery, Chiba Cancer Center, Chiba, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Ishii
mesh_terms: D000293:Adolescent; D000328:Adult; D001859:Bone Neoplasms / Q000473:pathology / Q000601:surgery*; D002648:Child; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D007564:Japan / Q000453:epidemiology; D008175:Lung Neoplasms / Q000556:secondary / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis / Q000453:epidemiology*; D009367:Neoplasm Staging; D012516:Osteosarcoma / Q000473:pathology / Q000601:surgery*; D011379:Prognosis; D012189:Retrospective Studies; D015996:Survival Rate; D013908:Thoracotomy; D055815:Young Adult