Prognostic Factors in Lobar World Health Organization Grade II Astrocytomas

BackgroundWorld Health Organization grade II astrocytomas (AII) are the commonest low-grade glioma subset, but their prognostic factors are subject to debate. This institutional study aimed to identify prognostic factors in lobar AII.MethodsRetrospective review of newly diagnosed, lobar AII between 2006 and 2012. Patient demographics, imaging, and treatment data were obtained. Isocitrate dehydrogenase-1 (IDH1) status was assessed via immunohistochemistry. Multivariate analysis was performed with Cox regression to identify prognostic factors for overall survival (OS) and progression-free survival (PFS).ResultsA total of 92 adult patients were identified with a median age of 42 years (range 20–73 years) and median follow-up period of 45 months (range, 7–98 months). Seizures were the commonest mode of presentation (75%). IDH1 immunopositivity was seen in 46 of 83 patients (55%). Radiology diagnosis agreed with histology in 76% of cases, and 28% of tumors had documented evidence of some degree of contrast enhancement. Surgical management was either resection (51%) or biopsy (49%) and postoperative radiotherapy was used in patients with unfavorable prognostic features. The median OS and PFS were 85 months (range 2–98 months) and 36 months (95% confidence interval [95% CI] 27–45 months), respectively. Surgical resection (P < 0.001; hazard ratio [HR] 5.072; 95% CI 2.050–12.550), absence of contrast enhancement (P = 0.006; HR 3.180; 95% CI 1.403–7.206), and IDH1 immunopositivity (P = 0.006; HR 3.310; 95% CI 1.416–7.738) were associated with improved OS. Good performance status (P = 0.005; HR 5.965; 95% CI 1.710–20.804) and absence of contrast enhancement (P < 0.001; HR 3.446; 95% CI 1.883–6.304) were associated with improved PFS.ConclusionsPatients with World Health Organization grade II astrocytomas have better overall survival if their tumor is nonenhancing, amenable to surgical resection, and exhibits the IDH1 mutation. These factors should be used to guide patient management and inform prognosis.