Materials and Methods: 135 patients who were irradiated for the diagnosis of GBM between March 1997 and June 2003 were studied. Median age was 60 years (range, 18-80 years) and the proportion of women to men was 53/82. Median preoperative and preRT KPS scores were both 80 (range, 30-100). Median symptom duration was 1 month (1-84 months) and 27% of patients had a history of seizures. Median tumor diameter was 4 cm (1-9 cm) and the rate of multicentric tumors was 13%. The location of the tumor was temporal in 28%, parietal in 27%, frontal in 23%, occipital in 11% and others in 11%. While the surgery was limited to stereotactic biopsy in 30% of the patients, subtotal resection was performed in 34% of the patients and gross total resection in 36%. Total RT dose was median 60 Gy (range, 9-72 Gy) for all patients.

Results: Median survival time was 9 months and overall survival rate for one year was 34% for all cases. Recurrence outside the irradiation area was demonstrated in only two of the cases after treatment. In univariate analysis; young age (p=0.0025), male sexuality (p=0.05), preRT KPS ≥70 (p=0.0003), preoperative KPS ≥70 (p=0.0002), having history of seizures (p=0.02), not being multicentric tumors (p=0.004) and complete surgical resection (p<0.0001) were determined as factors which correlated with improved overall survival. In multivariate analysis; age (p=0.006), multicentricity (p=0.002) and preRT KPS (p<0.0001) were determined as the independent prognostic factors.

Conclusion: Age, multicentricity, preRT KPS and gender were determined as the independent prognostic factors affecting survival after RT in patients with diagnosis of glioblastoma multiforme. Keywords : Glioblastoma multiforme, radiotherapy, survival, prognostic factor