Article
Risk factors for recurrence and malignant transformation of low grade astrocytomas
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Published: | April 28, 2011 |
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Objective: Low grade astrocytomas (LGA) are diffuse brain tumors of astrocytic origin, which are characterized in general by slow progression. Therefore, many patients present with mild symptoms and remain stable for years. However,some patients progress rapidly to higher-grade tumors with eventual neurologic decompensation and death. We investigated tumor-, patient-, and treatment-related prognostic factors to determine factors that were independently associated with recurrence and malignant transformation in adult patients with LGA.
Methods: Adult patients, who had craniotomy and resection for a hemispheric LGA (WHO Grade II) in our Department between 1993 and 2008 were retrospectively investigated. Multivariate proportional hazards regression analyses were used to identify associations with tumor recurrence and malignant degeneration. The data were categorized according to clinical data (age, gender, etc.), tumor-related factors (location, histology, immunhistochemistry, IDH mutations) and therapy related factors (adjuvant treatments, type of XRT, time to progression, survival).
Results: 50 consecutive patients with LGA were identified. in this series 31 (62%) and 25 (50%) patients experienced tumor recurrence and malignant degeneration at last follow-up, respectively. The 5- and 10-year OS rates were 72.7% and 57.7% respectively. Independent predictors of recurrence were tumor size, extent of the resection, radiation and tumor localization (p = 0.001). Independent factors associated with malignant degeneration were tumor size, radiation and gross-total resection (p = 0.001). IDH mutations were found in 36/50 patients (72%). IDH mutation was associated with prolonged overall survival but not with a prolonged progression free survival. Postoperative radiotherapy was applied to 11 (22%) patients with LGA. Radiotherapy was associated with improved PFS (67.2 months vs. 25 months) but not with a superior OS (124.8 vs. 90 months).
Conclusions: In this group of patients with low grade astrocytomas, the presence of IDH1 mutations was of strong prognostic significance for OS with evidence of a predictive significance for longer progression-free survival after radiotherapy. Patients with young age, gross or subtotal resection, one lobe tumor and postitive IDH1 mutation had the best progression-free and overall survival.