Genetic Factors Affecting Intraoperative 5-aminolevulinic Acid-induced Fluorescence of Diffuse Gliomas.

BACKGROUND: In patients operated for malignant glioma, 5-aminolevulinic acid (5-ALA)-induced fluorescence guidance is useful. However, we occasionally experience instances of non-visible fluorescence despite a histopathological diagnosis of high-grade glioma. We sought to identify factors that influence the intraoperative visualization of gliomas by their 5-ALA-induced fluorescence.

PATIENTS AND METHODS: We reviewed data from 60 patients with astrocytic or oligodendroglial tumors who underwent tumor removal under 5-ALA-induced fluorescence guidance between January 2014 and December 2015. Their characteristics, preoperative magnetic resonance imaging (MRI) findings, histological diagnosis, and genetic profile were analyzed and univariate and multivariate statistical analyses were performed.

RESULTS: In 42 patients (70%) we intraoperatively observed tumor 5-ALA fluorescence. They were 2 of 8 (25%) patients with World Health Organization (WHO) grade II, 9 of 17 (53%) with grade III, and 31 of 35 (89%) patients with grade IV gliomas. Univariate analysis revealed a statistically significant association between 5-ALA fluorescence and the isocitrate dehydrogenase 1 (IDH1) status, 1p19q loss of heterozygosity (LOH), the MIB-1 labeling index, and the tumor margin, -heterogeneity, and -contrast enhancement on MRI scans (p < 0.001, p = 0.003, p = 0.007, p = 0.046, p = 0.021, and p = 0.002, respectively). Multivariate analysis showed that the IDH1 status was the only independent, statistically significant factor related to 5-ALA fluorescence (p = 0.009).

CONCLUSIONS: This study identified the IDH1 status as the factor with the most influence on the 5-ALA fluorescence of diffuse gliomas.