gms | German Medical Science

48th Meeting of the Particle Therapy Co-Operative Group

Particle Therapy Co-Operative Group (PTCOG)

28.09. - 03.10.2009, Heidelberg

Whole ventricular irradiation for localised Intracranial Germinoma: arguments for proton therapy in comparison to IMRT and Tomotherapy

Meeting Abstract

  • C. Alapetite - Institut Curie Paris, Paris, France
  • L. De Marzi - Institut Curie Orsay, Orsay, France
  • S. Zefkili - Institut Curie Paris, Paris, France
  • C. Dauphinot - Institut Curie Paris, Paris, France
  • M. Amessis - Institut Curie Paris, Paris, France
  • S. Bolle - Institut Curie Paris, Paris, France
  • F. Lacroix - Institut Curie Orsay, Orsay, France
  • M. Robilliard - Institut Curie Paris, Paris, France
  • J.-L. Habrand - Institut Curie Orsay, Orsay, France
  • A. Mazal - Institut Curie Paris, Paris, France
  • R. Ferrand - Institut Curie Paris, Paris, France
  • P. Bey - Institut Curie Paris, Paris, France

PTCOG 48. Meeting of the Particle Therapy Co-Operative Group. Heidelberg, 28.09.-03.10.2009. Düsseldorf: German Medical Science GMS Publishing House; 2009. Doc09ptcog003

DOI: 10.3205/09ptcog003, URN: urn:nbn:de:0183-09ptcog0035

Published: September 24, 2009

© 2009 Alapetite et al.
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Outline

Text

Intracranial-Germinoma demonstrates excellent long-term survival after Craniospinal-irradiation plus Tumor-Bed Boost. Recent studies have examined combined approach with reduced radiation volume and/or dose.

SFOP-90 study delivered primary chemotherapy followed by 40 Gy to tumour-bed. At median follow-up 8.6yrs (2.4–15); 8yrs OS is 95%; EFS 84%+/-10. Pattern of relapse identified ventricular system as the area at risk of dissemination (8/10) marginal or outside radiation-fields. SIOP-96 study preliminary analysis shows similar pattern.

This led to propose for next SIOP-protocol, including whole-ventricular system (WV) at prophylactic dose 24 Gy, with 16 Gy boost at pineal and/or suprasellar primary site, when non-complete response to chemotherapy.

WV plus 5mm margin is a large, complex Clinical-Target-Volume justifying evaluating which RT-technique best improves the Radio-Therapeutic index.

Optimised 3DConformal (3fields), Linac based IMRT(Linac-IMRT) (5 fields) and helical-IMRT(Tomotherapy) plans, were compared to Proton Therapy(PT) plan (4 fields). Mean dose to supratentorial brain-PTV respectively is 15.5Gy; 14Gy; 13.6Gy and 9.8CGE. While Linac-IMRT plans improve conformity and spare additional amount of normal brain at higher doses in comparison to 3DCRT, this gain is obtained at the expense of an increased normal brain volume exposed to lower radiation-dose. Both characteristics are amplified using tomotherapy. In comparison, proton-beam delivery, using passive-scattering, offers high conformity and homogeneity and reduced supratentorial and infratentorial brain exposure both at higher and lower dose-levels (indeed, volume of the 8Gy isodose respectively is: 1451cc; 1596cc; 1751cc and 957cc). Active scanning delivery potentially further reduces the integral dose. Cumulative plans including 16Gy boost to primary site (pineal(2cases), suprasellar(1), bi-focal(2)), shows further benefit of PT, particularly for OAR non-abutting primary site PTV.

Forthcoming SIOP Intracranial-Germinoma study will be opened to the use of Proton beams. In the context of increasing number of Proton Therapy facilities around the world, developing this sophisticated radiation-treatment modality is of particular relevance considering the high percentage of long-term survivors, to best preserve these children from adverse late-effects including risk of secondary tumors.