Multivariate analysis of prognostic factors in patients with glioblastoma

Background: To identify prognostic factors for overall survival in patients with newly diagnosed glioblastoma undergoing radiation therapy. Patients and Methods: From January 1980 to June 2000, we treated 432 consecutive patients with glioblastoma at our institution. 17 patients were excluded from the analysis for various reasons. Mean age of the 415 patients who were included in the study was 59 years (19-81 years), Karnofsky performance status (KPS) was greater than or equal to70 in 280 patients. 343 patients underwent resection, 72 had a biopsy. Various fractionation schemes were used (conventional fractionation, n=112; hypofractionation, n=94; accelerated hyperfractionation, n=209). Survival probabilities were estimated using the method of Kaplan and Meier. Multivariate analysis was done with a Cox regression model. Results: By July 2001, 406 patients had died. Median overall survival was 8.2 months. Of ten factors considered in a proportional hazards model stratified for treatment (fractionation scheme and type of surgery), significant variables in a multivariate model were age (50-64 years vs <50 years [RR 1.35; 95% CI 1.02-1.78], &GE;65 years vs <50 years [RR 2.08; 95% CI 1.54-2.81]), performance status (KPS <70 vs &GE;70 [RR 1.53; 95% CI 1.23-1.90]), and central tumor Location (yes vs; no [RR 1.39; 95% CI 1.04-1.87]). Blood hemoglobin (Hb) values were available in 318 patients and serum Lactate dehydrogenase (LDH) levels in 234 patients. 89 patients were anemic (Hb men <13 g/dl, women <12 g/dl), in 80 patients the LDH Level was raised beyond the upper Limit of the normal range (>240 U/l). By including the three significant variables, both parameters had an additional significant effect with an estimated relative risk of about 1.4 in their corresponding subgroups. Conclusion: Besides established prognostic factors, anemia and raised serum LDH Levels may negatively influence outcome in glioblastoma patients. Our results from data-dependent modeling have to be confirmed by independent studies.