Radiation therapy for malignant gliomas in adults. Analysis of treatment results regarding factors on the radiation technique

During 19 years, 309 patients with astrocytic tumors (173 of glioblastoma multiforme (GBM), 41 of anaplastic astrocytoma (AA), and 95 of astrocytoma) were treated with radiation therapy. Initially a dose of 50 Gy was given with an extended field, then the target volume was decreased to the contrast enhancing lesion plus 1-2 cm margin and treated to the total dose ranging from 60 Gy to 66 Gy for GBM and about 60 Gy for AA. Fifty-four patients underwent surgical resection combined with a single dose of 15-20 Gy by intraoperative radiation therapy (IORT). The one-, 2-, and 3-year survival rates and the median survival time (MST) of patients with GBM were 56%, 27%, 16%, and 495 days, respectively. For patients with AA, these were 63%, 50%, 33%, and 762 days, respectively. From analysis on GBM, patients treated with IORT were survived longer than without IORT, significantly (p<0.01). However, no difference was observed on AA. Concerning the total dose, patients irradiated by 60-69 Gy and even or more than 70 Gy were survived longer than other groups. As for size of radiation field, patients treated with large portals, of which size was more than 150 cm2, were significantly inferior than with less portal size (p<0.05). Patients treated with conformation radiotherapy (CFRT) were superior on survival rates than without it on GBM, however, there was no difference on AA. The treatment factors for radiation therapy which affected for prolonging survival time were considered as dose, size of irradiated portals, application of IORT and CFRT, especially on patients with GBM. (author)