Effects of 5-ALA dose on resection of glioblastoma

Purpose: Fluorescence-guided surgery (FGS) with the use of 5-aminolevulinic acid (5-ALA) leads to more extensive resection of high-grade glioma (HGG) and longer overall survival (OS) of patients compared to conventional resection. The purpose of this study is to investigate the effect of 5-ALA dosages on residual tumor volume (RTV) and OS in patients with glioblastoma. Methods: A retrospective cohort study for patients who participated in a phase I and II dose-escalation clinical trial on 5-ALA for resection of HGG. A total of 25 patients were found to have newly diagnosed glioblastoma on histology and enrolled in our study. Patients receiving low doses of 5-ALA (10–30 mg/kg) (n = 6) were compared to those receiving high doses (40–50 mg/kg) (n = 19). Pre- and post-operative contrast enhanced T1W MRI were evaluated with volumetric analysis. Results: Median RTV was 0.69 cm ³ and 0.00 cm ³ in the low and high dose groups respectively (p = 0.975). A gross total resection (GTR) was more likely in the high dose group, though this was not statistically significant. No significant difference was found in median OS between the high and low dose groups (p = 0.6787). Conclusions: High doses of 5-ALA FGS are associated with less RTV and greater probability of GTR. 5-ALA dose was not associated with OS. Further studies with a larger patient cohort are warranted.