title: Ewing's sarcoma: only patients with 100% of necrosis after chemotherapy should be classified as having a good response.
abstract: OBJECTIVE
  The purpose of this study was to review a large cohort of patients and further assess the correlation between the histological response to chemotherapy in patients with Ewing's sarcoma with the overall (OS) and event-free survival (EFS).
  
  
  METHODS
  All patients treated for Ewing's sarcoma between 1980 and 2012 were reviewed. Of these, 293 patients without metastases at the time of diagnosis and treated with chemotherapy and surgery were included. Patients were grouped according to the percentage of necrosis after chemotherapy: Group I: 0% to 50%, Group II: 51% to 99% and Group III: 100%.
  
  
  RESULTS
  The mean age at diagnosis was 16 years (1 to 62) and the mean follow-up was 9.1 years (six months to 32.6 years). The OS and EFS for the series were 75% and 65% at five years. There were significant differences in survival between the groups of necrosis: 0% to 50% (OS: 49% and EFS: 45% at five years, respectively) compared with 51% to 99% (OS: 72% and EFS: 59% at five years, respectively) and 100% (OS: 94% and EFS: 81% at five years, respectively) (p < 0.001). There were no significant differences in survival between patients treated between 1980 and 1989 compared with those treated between 1990 and 1999, and those treated between 2000 and 2012 (p = 0.55).
  
  
  CONCLUSIONS
  Only patients with 100% necrosis after chemotherapy should be classified as having a good response to chemotherapy because they have significantly better rates of survival compared with those with any viable tumour in the surgical specimen. Cite this article: Bone Joint J 2016;98-B:1138-44.
authors.affiliation: Royal Orthopaedic Hospital, Northfield, Birmingham, UK.
authors.forename: J I
authors.initials: JI
authors.lastname: Albergo
authors.affiliation: Royal Orthopaedic Hospital, Northfield, Birmingham, UK.
authors.forename: C L
authors.initials: CL
authors.lastname: Gaston
authors.affiliation: Royal Orthopaedic Hospital, Northfield, Birmingham, UK.
authors.forename: M
authors.initials: M
authors.lastname: Laitinen
authors.affiliation: Royal Orthopaedic Hospital, Northfield, Birmingham, UK.
authors.forename: A
authors.initials: A
authors.lastname: Darbyshire
authors.affiliation: Royal Orthopaedic Hospital, Northfield, Birmingham, UK.
authors.forename: L M
authors.initials: LM
authors.lastname: Jeys
authors.affiliation: Royal Orthopaedic Hospital, Northfield, Birmingham, UK.
authors.forename: V
authors.initials: V
authors.lastname: Sumathi
authors.affiliation: Royal Orthopaedic Hospital, Northfield, Birmingham, UK.
authors.forename: M
authors.initials: M
authors.lastname: Parry
authors.affiliation: Royal Orthopaedic Hospital, Northfield, Birmingham, UK.
authors.forename: D
authors.initials: D
authors.lastname: Peake
authors.affiliation: Royal Orthopaedic Hospital, Northfield, Birmingham, UK.
authors.forename: S R
authors.initials: SR
authors.lastname: Carter
authors.affiliation: Royal Orthopaedic Hospital, Northfield, Birmingham, UK.
authors.forename: R
authors.initials: R
authors.lastname: Tillman
authors.affiliation: Royal Orthopaedic Hospital, Northfield, Birmingham, UK.
authors.forename: A T
authors.initials: AT
authors.lastname: Abudu
authors.affiliation: Royal Orthopaedic Hospital, Northfield, Birmingham, UK.
authors.forename: R J
authors.initials: RJ
authors.lastname: Grimer
mesh_terms: D000293:Adolescent; D000328:Adult; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D001859:Bone Neoplasms / Q000188:drug therapy* / Q000401:mortality / Q000601:surgery; D002648:Child; D002675:Child, Preschool; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D007223:Infant; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D009336:Necrosis; D010386:Pelvic Neoplasms / Q000188:drug therapy / Q000401:mortality / Q000601:surgery; D011446:Prospective Studies; D012512:Sarcoma, Ewing / Q000188:drug therapy* / Q000401:mortality / Q000601:surgery; D013125:Spinal Neoplasms / Q000188:drug therapy / Q000401:mortality / Q000601:surgery; D013899:Thoracic Neoplasms / Q000188:drug therapy / Q000401:mortality; D016896:Treatment Outcome; D055815:Young Adult
keywords: Event free survival; Ewing sarcoma; Histological response; Overall survival