Partial brain irradiation [PBI] or whole brain irradiation [WBI], the justified solution in the management of patients with malignant astrocytomas

ABSTRACT

Postoperative conventional radiotherapy [RT] improved survival for glioblastoma multiforme [GBM] and astrocytoma anaplasticum [AA], but local recurrences were still a reason of poor outcome. The optimum RT in GBM and AA patients has not been clearly defined by prospective randomized trials. Today, individually constructed partial brain irradiation [PBI] remains to be accepted model, but, however, controversies still exist with respect to its size. The main purpose of this study was to compare response and acute radiation toxicity in patients with malignant astrocytoma treated by PBl or whole brain irradiation [WBI]. Thirty-four patients with supratentorial malignant astrocytomas were enrolled in this study and treated between January 2003 and December 2004 in the Clinical Oncology Department, Faculty of Medicine, Alexandria University. Patients were randomized in two therapeutic groups according to the used treatment volume. In group I PBI covered the contrast-enhancing lesion with 2 cm added margins. The dose was 50 Gy/25 fractions over 5 weeks followed by boost dose of 15 Gy/5 fractions per week. Group II patients were treated by WBI to a dose of 40 Gy/20 fractions and a boost dose of 25 Gy in 12 fractions. Complete response was achieved in 35.3% and 11.8% of patients in group I and group II respectively. Improvement of KPS to 90-100% by 76.5% of group I and 41.2% of group II [p=0.0365]. Four patients had recurrence in both groups I and II with a median recurrence time of 6.8 and 4.5 months respectively. The median survival time was 9.95 months for group I and 9.54 for group II [p=0.761] and the one year overall survival of both groups I and II was 59% and 48% respectively. Although the limitation of the treatment volume does not prolong the duration of survival, its application is justified to decrease brain necrosis. Due to rescuing the normal brain tissue, PBI leads to a possibility for applying high radiation doses that could improve the local tumor control and more exact localization of the lesion contributes to more efficient treatment