Photodynamic diagnosis using 5-aminolevulinic acid in surgery for spinal cord astrocytic tumors: a propensity score-matched comparison with brain tumors.

Abstract

Photodynamic diagnosis (PDD) using 5-aminolevulinic acid (5-ALA) has proven to be an effective method for visualizing the tumor during surgery. The purpose of this study was to verify the practicality of PDD in the surgery of astrocytic tumors of the spinal cord, with particular emphasis on comparison with astrocytic tumors of the brain. This retrospective study included the cases of astrocytic tumors of the spinal cord and brain that were treated with initial surgery at the authors' institution between April 2023 and March 2025. The PDD and pathological characteristics were compared between spinal cord and brain tumors. A propensity score-matched analysis was performed to reduce covariate bias between the cohorts. There were 13 cases of astrocytic tumors in the spinal cord and 43 cases of those in the brain; 5-ALA-induced protoporphyrin IX (PpIX) fluorescence was observed considerably less frequently in spinal cord astrocytic tumors (15.4%) than in those in the brain (69.8%). Pathological analysis revealed a tendency for the malignant form to be more prevalent in the brain. A notable finding was that all 13 cases of spinal cord tumors were found to be the isocitrate dehydrogenase 1 (IDH1) wildtype. The propensity score-matched analysis suggested that the detection of PpIX fluorescence was found to be significantly less prevalent in the spinal cord. The findings of this study suggest that PDD may be less effective in the surgery of astrocytic tumors of the spinal cord compared with those of the brain. Verifying the molecular differences of astrocytic tumors between the spinal cord and brain in a large number of cases will be necessary in future studies.