Impact of radiotherapy parameters on outcome for patients with supratentorial primitive neuro-ectodermal tumours entered into the SIOP/UKCCSG PNET 3 study.

Abstract

BACKGROUND AND PURPOSE:

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 AND MATERIALS:

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: Roger E Taylor, Paul H J Donachie, Claire L Weston, Kathryn J Robinson, Helen Lucraft, Frank Saran, David W Ellison, James Ironside, David A Walker, Barry L Pizer, Children's Cancer and Leukaemia Group CNS Tumour Division
• Journal: Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology (Radiother Oncol) Vol. 92 Issue 1 Pg. 83-8 (Jul 2009) ISSN: 1879-0887 [Electronic] Ireland
• PMID: 19328574 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Topics

• Adolescent
• Child, Preschool
• Combined Modality Therapy
• Disease-Free Survival
• Female
• Humans
• Male
• Neoplasm Recurrence, Local (drug therapy, radiotherapy)
• Neuroectodermal Tumors, Primitive (drug therapy, radiotherapy)
• Radiation Dosage
• Randomized Controlled Trials as Topic
• Supratentorial Neoplasms (drug therapy, radiotherapy)
• Treatment Outcome