Quality assurance of the EORTC 26981/22981; NCIC CE3 intergroup trial on radiotherapy with or without temozolomide for newly-diagnosed glioblastoma multiforme: the individual case review.

The phase III randomised European Organisation for Research and Treatment of Cancer (EORTC) and National Cancer Institute of Canada Clinical Trail Group (NCIC) Intergroup trial (EORTC 26981/22981; CE3) compares irradiation alone with irradiation plus temozolomide for patients with glioblastoma multiforme (GBM). We evaluated the compliance to radiotherapy (RT) guidelines. All 85 recruiting centres were invited to participate in the individual case review. Fifty-four centres (64%) entering 71% of the patients provided data on one randomly selected patient. All participating centres used individual head immobilisation and computerised tomography (CT)-based treatment planning. Most (74%) performed three-dimensional conformal radiotherapy (3-D-CRT) including dose-volume histograms. Ninety-four percent performed portal imaging at least once. Planning target volume (PTV) and structures at risk were delineated in most of the centres (94%). Although the PTV received < 95% of the prescription dose (60 Gy in 2 Gy/fraction/day) in 39% of the centres; all except 2 centres delivered 50-60 Gy to the PTV. The maximum dose to the critical structures exceeded the protocol dose constraints in 39% of the reviewed patients, but in only 9% was this over the acceptable tolerance dose reported in the literature. We found a high rate of compliance with the protocol and general RT guidelines in the centres participating in this individual case review. In multicentre trials with a large of number of investigators from international and national groups, it is essential to confirm the interinstitutional consistency, qualitatively and quantitatively.