5-year survival and clinical prognostic factors in progressive supratentorial diffuse ''low-grade'' astrocytoma: A retrospective analysis of 46 cases

In order to study survival and identify prognostic factors in progressive supratentorial low grade astrocytoma, 46 cases of diffusely growing glioma (1982-1989), in which stereoractic biopsy revealed a diagnosis of astrocytoma grade II according to Kernohan, were evaluated. Only patients with definite tumour growth on consecutive CT scans were included. All patients received a full course of fractionated radiotherapy. All tumour biopsy specimens were re-evaluated according to both the Kernohan and Daumas-Duport grading systems. Follow-up for at least 5 years showed a median survival of 47.5 months (1 year 71%, 5 year 41%). In Cox' multivariate analysis 4 factors turned out to give the best fitting prognostic model for survival: age, duration of symptoms, pre operative neurological examination and CT-contrast enhancement. Numerical scoring was performed by giving either 1 or 0 for: age> or <40 years, symptom duration [or] 1 year, presence or absence of focal deficit, and presence or absence of CT-contrast enhancement. Combining these factors in a score ranging from 0-4 re suited in 3 distinct groups with respect to median survival (<2:66.5 months, 2:40 months, >2:10 months, P=0.0015). Although 17 cases with Kernohan grade II were upgraded using Daumas-Duport criteria (13 grade III, 4 grade IV), these cases did not form a separate survival-group. Additional parameters are needed to assess prognosis by neuropathological means, as some ''low-grade'' rumours are less benign than others, giving rise to a variable natural history.