Medical Student Donald and Barbara Zucker School of Medicine at Hofstra/Northwell Boyds, Maryland, United States
Introduction: 5-aminolevulinic acid (5-ALA) fluorescence guided surgery (FGS) permits neurosurgeons to better visualize the tumor-brain interface in real-time intraoperatively. 5-ALA FGS in high grade gliomas significantly increases extent of resection (EOR) with positive effects on outcomes over traditional white light microscopy. However, consensus regarding the utility of 5-ALA in other brain tumors, namely brain metastases, is poorly described despite brain metastases being the most common intracranial tumor. We systematically reviewed existing literature regarding 5-ALA FGS for brain metastases.
Methods: We searched the PubMed database for studies involving 5-ALA and brain metastases, adhering to PRISMA guidelines. Predetermined inclusion and exclusion criteria were applied to identify studies investigating 5-ALA use in brain metastasis resection, and studies were categorically analyzed to identify tumor primary sites or histological subtypes and respective fluorescence rates.
Results: Our initial search identified 421 studies, of which 10 met inclusion criteria. Of these studies, 6 were retrospective in design and 4 were prospective, evaluating a total of 631 patients with brain metastases. Reported rates of 5-ALA fluorescence varied from 28% to 87% between studies. Rates of fluorescence by primary site varied from 36% in melanoma brain metastases, to 54% in breast cancer brain metastases, although no statistically significant relationship was observed between any primary site and fluorescence. No studies identified improved extent of resection or survival statistics from 5-ALA use.
Conclusion : Brain metastases demonstrate variable 5-ALA induced fluorescence both between and within metastatic tumor types. Current evidence does not support an improved EOR or improvements in patient outcomes. Further studies evaluating primary tumor molecular and genetic profiles and modifying delivery algorithms are necessary to better define the relationship with 5-ALA fluorescence in brain metastasis.
