• Mariangela Massaccesi, Marica Ferro, Savino Cilla, Mario Balducci, Francesco Deodato, Gabriella Macchia, Vincenzo Valentini, and Alessio G Morganti.
• Radiotherapy Unit, Department of Oncology, Fondazione di Ricerca e Cura "Giovanni Paolo II", Università Cattolica del S. Cuore, Largo A. Gemelli 1, 86100, Campobasso, Italy.
• Int. J. Clin. Oncol. 2013 Oct 1; 18 (5): 784-91.

BackgroundWe performed a dose-escalation trial to determine the maximum tolerated dose (MTD) of intensity-modulated radiotherapy (IMRT) with standard concurrent and sequential-dose temozolomide (TMZ) in patients with glioblastoma multiforme.MethodsHistologically proven glioblastoma patients underwent IMRT dose escalation. IMRT was delivered over 5 weeks with the simultaneous integrated boost (SIB) technique to the two planning target volumes (PTVs) defined by adding 5-mm margin to the respective clinical target volumes (CTVs). CTV1 was the tumor bed plus the enhancing lesion with 10-mm margin; CTV2 was the area of perifocal edema with 20-mm margin. Only the PTV1 dose was escalated (planned dose escalation: 60, 62.5, 65, 67.5, 70 Gy) while the PTV2 dose remained the same (45 Gy).ResultsForty consecutive glioblastoma patients were treated. While no dose-limiting toxicity (DLT) was recorded during the dose escalation up to 67.5/2.7 Gy, two out of the first six consecutively enrolled patients on the highest dose level (70/2.8 Gy) experienced a DLT, and therefore a cohort expansion was required. 3/14 patients experienced a DLT on the highest planned dose level, and therefore the MTD was not exceeded. After a median follow-up time of 25 months no grade >2 late neurological toxicity was recorded.ConclusionsBy using a SIB IMRT technique, a radiation dose of 70 Gy in 25 fractions (biological effective dose--BED--of 92.8 Gy) can be delivered with concurrent and sequential standard dose TMZ, without unacceptable acute toxicity in patients with glioblastoma.

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