Brain metastasis (BrM) is a major problem associated with cancer-related mortality, and currently, no specific biomarkers are available in clinical settings for early detection. Liquid biopsy is widely accepted as a non-invasive method for diagnosing cancer and other diseases. We have reviewed the evidence that shows how the molecular alterations are involved in BrM, majorly from breast cancer (BC), lung cancer (LC), and melanoma, with an inception in how they can be employed for biomarker development. We discussed genetic and epigenetic changes that influence cancer cells to breach the blood-brain barrier (BBB) and help to establish metastatic lesions in the uniquely distinct brain microenvironment. Keeping abreast with the recent breakthroughs in the context of various biomolecules detections and identifications, the circulating tumor cells (CTC), cell-free nucleotides, non-coding RNAs, secretory proteins, and metabolites can be pursued in human body fluids such as blood, serum, cerebrospinal fluid (CSF), and urine to obtain potential candidates for biomarker development. The liquid biopsy-based biomarkers can overlay with current imaging techniques to amplify the signal viable for improving the early detection and treatments of occult BrM.

中文翻译：

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隐匿性脑转移的液体活检

脑转移 (BrM) 是与癌症相关死亡率相关的一个主要问题，目前，临床环境中没有可用于早期检测的特定生物标志物。液体活检作为诊断癌症和其他疾病的非侵入性方法被广泛接受。我们已经审查了显示分子改变如何参与 BrM 的证据，主要来自乳腺癌 (BC)、肺癌 (LC) 和黑色素瘤，并开始研究如何将它们用于生物标志物开发。我们讨论了影响癌细胞突破血脑屏障 (BBB) 并有助于在独特的大脑微环境中建立转移性病变的遗传和表观遗传变化。紧跟最近在各种生物分子检测和鉴定方面的突破，循环肿瘤细胞 (CTC)、游离核苷酸、非编码 RNA、分泌蛋白和代谢物可以在人体体液如血液、血清、脑脊液 (CSF) 和尿液中进行追踪，以获得潜在的生物标志物候选物发展。基于液体活检的生物标志物可以与当前的成像技术叠加，以放大可行的信号，以改善隐匿性 BrM 的早期检测和治疗。