Emerging blood-based biomarkers for the detection of parenchymal brain metastasis: current progress and future perspectives

Parenchymal brain metastases of solid malignancies remain a significant clinical challenge, as they are often detected at later symptomatic stages, which are typically associated with worse prognosis. Delayed detection limits treatment options and contributes to poor outcomes, while early detection is critical for improving patient outcomes and quality of life. In this comprehensive review, we investigated the potential use and challenges of blood-based biomarkers, including circulating tumor cells, cell-free DNA, noncoding RNAs, extracellular vesicles, proteins, and other immune-related biomarkers, for the early detection of parenchymal brain metastasis. The use of blood-based liquid biopsies offers a promising avenue for early detection and monitoring of brain metastases, potentially enabling timely intervention and tailored treatment regimes. Continued research and rigorous clinical validation are essential to fully harness the potential of blood-based biomarkers, which could transform clinical practice in oncology.