In addition to stereotactic localization as well as intraoperative brain mapping, techniques to enhance visual identification of tumor intraoperatively may be used and include 5-aminolevulinic-acid (5-ALA). 5-ALA is metabolized into fluorescent porphyrins, which accumulate in malignant glioma cells. These property permits use of ultraviolet illumination during surgery as an adjunct to map out the tumor. This has been proven with RCT where the use of 5-ALA leads to more complete resection (65% vs. 36%, p < 0.0001), which translates into a higher 6-month progression-free survival (41% vs. 21.1%, p = 0.0003) but no effect on OS 1)
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Stummer W, Pichlmeier U, Meinel T, et al. Fluorescence-guided surgery with 5-aminolevu- linic acid for resection of malignant glioma: a randomised controlled multicentre phase III trial. Lancet Oncol. 2006; 7:392–401