Utility of 5-ALA for fluorescence-guided resection of brain metastases: a systematic review

Purpose 5-aminolevulinic acid (5-ALA) has demonstrated its utility as an intraoperative imaging adjunct during fluorescence guided resection of malignant gliomas. However, literature regarding 5-ALA-guided resection for brain metastases is limited. We conducted a systematic review to evaluate the efficacy of 5-ALA fluorescence for resection of metastatic brain tumors. Methods PubMed was queried for studies involving 5-ALA and brain metastases, and results were screened following PRISMA guidelines. Articles related to 5-ALA and brain metastasis were further assessed based on inclusion and exclusion criteria and results were analyzed for 5-ALA fluorescence rates stratified by tumor primary sites and histological subtypes. Results Of 421 identified search results, 10 studies were included and a total of 631 patients analyzed. Of these studies, 60% were retrospective in design. The reported rates of 5-ALA fluorescence in included brain metastases ranged from 27.6 to 86.9%, with variability across and within tumor types. No studies concluded improved operative outcomes or survival outcomes related to 5-ALA use. Conclusions Current studies regarding 5-ALA fluorescence in brain metastases are limited and do not confirm efficacy for improving extent of resection or post-operative survival. Fluorescence is variable across and within tumor types. Further studies are necessary to evaluate whether specific tumors may benefit from 5-ALA FGS or if changes in delivery protocols or fluorescence quantification may affect intraoperative utility.