Impact on radiation dose and volume of the brain on recurrence and survival of patients with glioblastoma multiformae
Introduction: Purpose of this study is analyzing impact of irradiated brain volume on survival and time to progression of patients with glioblastoma.
Materials and methods: Dosimetric analysis of treatment plan data has been performed on 70 patients with glioblastoma, treated with postoperative radiochemotherapy with temozolomide, followed by adjuvant temozolomide. Patients were treated with 2 different methods of definition of treatment volumes and prescription of radiation dose. First group of patients has been treated with one treatment volume receiving 60 Gy in 2 Gy daily fraction (31 patients) and second group of the patients has been treated with “cone-down” technique, which consisted of two phases of treatment: the first phase of 46 Gy in 2 Gy fraction followed by “cone-down” boost of 14 Gy in 2 Gy fraction (39 patients). Quantification of “V57Gy”, volume receiving 57 Gy and more and ratio between brain volume and “V57Gy” has been done. Average values of both parameters have been taken as a threshold value and patients have been split into 2 groups for each parameter (smaller and lager than threshold value).
Results: Mean value for Volume “V57 Gy” was 593.39 cm3 (range 166.94 to 968.60 cm3), Mean value for brain volume has been measured as 1332.86 cm3 (range 1047.00 to 1671.90 cm3) and mean value for ratio of brain and “V57Gy” has been 2.46 (range 1.42 to 7.67). There was no significant difference between two groups for both “V57Gy” and ratio between brain volume and “V57Gy”.
Discussion: Irradiated volume with dose more than 57Gy (“V57Gy) and ration between whole brain volume and “V57Gy” does not have any impact on recurrence and survival of patients with glioblastoma.