Tumour surface area as a prognostic factor in primary and recurrent glioblastoma irradiated with 192Ir implantation

SummaryBackgroundTo evaluate the impact of tumour surface area (TSA) on survival of patients treated with 192Ir implantation for glioblastoma multiforme (GBM).Methods/MaterialsThe analysis of survival and prognostic factors was performed based on a retrospective study group of 120 patients (74 males and 46 females; mean age 53 years; mean KPS score 74.6) irradiated with 192Ir for GBM between 1999 and 2003. There were 72 (60%) patients with recurrent and 48 (40%) with primary inoperable tumour. Patients with recurrences were initially treated with surgery and external beam radiotherapy (EBRT; mean total dose (MTD) 53.5Gy). Individuals with primary inoperable glioblastoma underwent EBRT (MTD 37.2Gy) after brachytherapy completion. All patients were irradiated with 192Ir with a total dose of 15Gy given in 5 fractions.ResultsFor the total group of patients 1-year and 2-year survival were 22% and 11%, respectively, with a median survival time (MST) of 6.1 months. The multivariate Cox analysis of the best fit (Chi2=22.98, p=0.000041) distinguished such variables as: patient age (p=0.002), performance status (p=0.04) and tumour surface area (p=0.04) to significantly affect survival. Patients with TSA<90 cm2 had better prognosis compared to those with TSA≥90cm2 (p<0.001).ConclusionsTumour surface area is an independent prognostic factor in patients irradiated with 192Ir for glioblastoma multiforme. TSA less than 90cm2 predicts significantly longer survival and appears to be a more powerful prognostic variable than tumour volume.