5-Aminolevulinic acid fluorescence indicates perilesional brain infiltration in brain metastases

Abstract Objective In glioma surgery, 5-aminolevulinic acid (5-ALA) fluorescence reflects tumor infiltration and fluorescence-assisted resection correlates with higher removal rates and improved progression free survival. Recent studies reported that a sizeable proportion of brain metastases exhibit peritumoral infiltration on the cellular level. There is little information on whether 5-ALA is useful to guide surgery in the peritumoral zone in mestastases. The aim of this study is to assess histologically whether 5-ALA fluorescence accurately reflects metastatic brain infiltration. Patients and Methods A total of 27 patients with brain metastases underwent fluorescence-assisted tumor resection. Patients received 20 mg/kg 5-ALA three hours before anesthesia. After resection, biopsies of the surrounding parenchyma were analyzed for 5-ALA fluorescence and histological evidence of infiltrating tumor cells. Furthermore, we assessed the correlation between 5-ALA positivity and immunohistochemical evidence of tumor in the peritumoral zone. Results 23/27 (85%) of metastases were 5-ALA positive. A total of 110 out of 125 samples were collected for qualitative tissue analysis. N=49 samples with faint or red fluorescence revealed metastatic infiltration and 33 samples without fluorescence were tumor-free. The presence of metastatic infiltration correlated with fluorescence (p Conclusion Affection of surrounding brain tissue is a common finding in brain metastases in selected primary tumors. 5-ALA fluorescence correlates with tumor cell infiltration and might guide more radical resection.