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

Abstract
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 stereotactic 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, preoperative 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 resulted 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” tumours are less benign than others, giving rise to a variable natural history.