Fluorescence-Guided Surgery

Before surgery, the patient drinks a medication called 5-ALA. Tumor cells absorb it and convert it into a compound that collects inside the tumor. When the surgeon shines blue light from the operating microscope, that compound gives off a pink-red glow, while healthy brain tissue stays a dull blue. The glow marks tumor that can be hard to see under ordinary white light.

5-ALA, short for 5-aminolevulinic acid, is an oral liquid sold under the brand name Gleolan. The patient drinks it a few hours before brain surgery. It is not a treatment for the tumor itself. Its job is to make high-grade glioma tissue glow under blue light so the surgeon can see tumor edges more clearly during the operation. The FDA approved it for this use in 2017.

The randomized trial behind FDA approval found that surgeons using 5-ALA removed all of the contrast-enhancing tumor in roughly 65 percent of patients, compared with about 36 percent using white light alone, with more patients free of progression at six months. More complete removal is associated with better outcomes. The technique improves how well tumor can be seen, but it does not guarantee any individual result.

The drug temporarily makes skin and eyes more sensitive to bright light, a side effect called photosensitivity. For about 48 hours after the drink, strong sunlight or bright indoor light can cause a reaction similar to a sunburn. Staying in lower light and out of direct sun during that window lets the effect wear off. The care team gives specific instructions before discharge.

No. It is a standard craniotomy with two additions: the patient drinks the 5-ALA solution beforehand, and the surgeon switches the microscope to blue light at points during the resection. The opening in the skull, the removal of tumor, and the recovery all follow the usual path. The fluorescence is a visualization tool layered onto the operation.

No. High-grade gliomas, including glioblastoma, tend to glow reliably. Lower-grade tumors often do not. In published studies, visible fluorescence appears in only about 16 to 20 percent of Grade 2 gliomas. The FDA label is also clear that tissue without glow can still contain tumor, so the absence of a glow does not prove an area is free of disease.

Fluorescein is another fluorescent agent sometimes used in glioma surgery. It is given by injection, costs less, and can be used on shorter notice. It works differently: it tends to mark areas where the brain's protective barrier has broken down rather than the tumor cells themselves, which can make it less specific at the infiltrating edge. 5-ALA has the larger body of randomized evidence and FDA approval for high-grade glioma visualization.

No. Fluorescence is one input among several. The surgeon still uses the operating microscope, neuronavigation, and pre-operative MRI, and removal is always limited by what can be taken out safely without harming areas that control speech, movement, and other functions. The goal is maximal safe resection, and the final diagnosis comes from pathology, not the glow.

Dr. Sherman is a co-author of a prospective, multicenter study of 5-ALA fluorescence in high-grade glioma surgery published in the Journal of Neurosurgery in 2022. He treats high-grade gliomas and glioblastoma at Rutgers Cancer Institute in New Brunswick, NJ, the only NCI-designated comprehensive cancer center in the state.