title: Impact of radiotherapy parameters on outcome for patients with supratentorial primitive neuro-ectodermal tumours entered into the SIOP/UKCCSG PNET 3 study.
abstract: OBJECTIVE
  To evaluate the impact of radiotherapy (RT) parameters on outcome in the SIOP/UKCCSG study of pre-RT chemotherapy for Supratentorial Primitive Neuro-ectodermal Tumours.
  
  
  METHODS
  Sixty-two patients aged 2.9-16.6 (median 6.4 years) were eligible. Forty-eight (77%) had non-pineal sites and 14 (23%) had pineal sites. Eleven were randomized to RT alone (6) and five to pre-RT Vincristine, Etoposide, Carboplatin and Cyclophosphamide. Fifty-one were not randomized, 15 receiving RT alone and 36 receiving pre-RT chemotherapy. Craniospinal RT (CSRT) 35 Gy/21 fractions were followed by 20 Gy/12 fractions to primary tumour.
  
  
  RESULTS
  Mean CSRT dose was 34.7 Gy and mean total primary dose was 53.4 Gy for those who received radiotherapy. Of 30 relapses, 18 (60%) were local only and 5 (16.7%) were combined local and leptomeningeal. There was no significant impact on Overall Survival (OS) or Event-Free Survival (EFS) of surgery-RT interval for patients treated by pre-RT chemotherapy or RT alone, or duration of RT (completing within 50 days). Planning films were received for 42/54 (77.8%) patients. Fourteen (33%) had one or more targeting deviations (10 cribriform fossa, 11 base of skull). There was a statistically significant increase in the risk of recurrence for patients with cribriform fossa targeting deviations (p=0.033), but not for patients with base of skull targeting deviations (p=0.242). There was no statistically significant difference in OS (p=0.0598) or EFS (p=0.0880) for patients who had one or more targeting deviations compared to those who had none.
  
  
  CONCLUSIONS
  This study has not demonstrated a statistically significant impact of radiotherapy duration or targeting deviations on OS or EFS, possibly due to small patient numbers. However, multi-institutional SPNET trials should incorporate quality assurance programs including analysis of relapse pattern in relation to primary target volume coverage.
authors.affiliation: Swansea University, Swansea, UK. Roger.Taylor@Swansea-tr.wales.nhs.uk
authors.forename: Roger E
authors.initials: RE
authors.lastname: Taylor
authors.forename: Paul H J
authors.initials: PH
authors.lastname: Donachie
authors.forename: Claire L
authors.initials: CL
authors.lastname: Weston
authors.forename: Kathryn J
authors.initials: KJ
authors.lastname: Robinson
authors.forename: Helen
authors.initials: H
authors.lastname: Lucraft
authors.forename: Frank
authors.initials: F
authors.lastname: Saran
authors.forename: David W
authors.initials: DW
authors.lastname: Ellison
authors.forename: James
authors.initials: J
authors.lastname: Ironside
authors.forename: David A
authors.initials: DA
authors.lastname: Walker
authors.forename: Barry L
authors.initials: BL
authors.lastname: Pizer