Supratentorial World Health Organization Grade 2 astrocytomas and oligoastrocytomas. A new pattern of prognostic factors

BACKGROUND: Prognostic factors for adult patients with supratentorial World Health Organization (WHO) Grade 2 astrocytomas and poorly defined. METHODS: The prognostic importance of pretreatment patient- and tumor-related factors was analyzed retrospectively in 197 adult patients with supratentorial astrocytomas (n = 153) or oligoastrocytomas (n = 44) using the multivariate Cox proportional hazards model. Endpoints were death and date of malignant transformation. All patients were treated similarly between 1979 and 1992 with iodine-125 implants as the primary treatment. RESULTS: A new prognostic pattern was detected. Unfavorable prognostic factors with regard to survival were 1) a tumor volume > or = 20 mL; 2) a performance status < or = 80; and 3) age > or = 40 years for the female subpopulation. Midline shift (another important tumor-related factor after univariate analysis) was highly correlated with tumor volume and therefore not included in the multivariate model. Risk factors of malignant transformation were 1) a tumor volume > or = 20 mL; 2) an enhancement in the computed tomography scan; and 3) age > or = 40 years for the female subpopulation. Prognostic factors created subsets of patients with 5-year survival rates ranging from as low as 5% to as high as 79%. CONCLUSIONS: Any treatment decision or evaluation of treatment efficacy should take into account the strong influence of both patient- and tumor-related factors. Any further study design should consider the detected interaction between gender and age and the importance of tumor volume.