Gliomas are tumors that occur in all ages; they include the most common malign primary central nervous system tumors in developed countries. Gliomas are often aggressive, and their recommended treatment is surgical resection and chemoradiation. Complete tumor removal is challenging because of diffuse cell growth and the proximity of functionally critical tissues. Surgeons use 5-aminolevulinic acid (5-ALA) drug-induced fluorescence to visually detect tumor cells, which improves resection rates and delays tumor progression. Tumor cells are often left unnoticed because of visual obstacles or weak fluorescence, which may lead to local recurrence and reoperations. Surgical suction devices are used to remove cancerous tissues, but so far the suction aspirate tissues have not been routinely used in tissue detection. This single-center observational study compares experts' visual detection of 5-ALA-induced fluorescence and fluorescence detected from the surgical suction waste. The fluorescence from the suction waste will not be reported back to the surgeon.