Liquid biopsies have been receiving tremendous attentions as easy, rapid, and non-invasive tools for cancer diagnosis. Liquid biopsy can be performed repeatedly for disease monitoring and is expected to overcome the limitations of tissue biopsies. With the advancement of next generation sequencing technologies, it is now possible to detect minute amount of tumor-derived circulation tumor DNA (ctDNA) from blood samples. Importantly, ctDNA detection could be complementary to tissue biopsies or tumor biomarkers particularly in cases of which tumor biopsy is clinically difficult to obtain. Here, we introduce the up-to-date technologies used in cfDNA-based liquid biopsy and review the clinical utilities of ctDNA in cancer screening, detection of minimal residual diseases, selection of molecular-targeted drugs, as well as monitoring of treatment responsiveness. We also discuss the challenges and future perspectives of liquid biopsy implementation in clinical setting.

液体活检作为一种简单、快速和非侵入性的癌症诊断工具受到了极大的关注。液体活检可重复进行疾病监测，有望克服组织活检的局限性。随着新一代测序技术的进步，现在可以从血液样本中检测出微量的肿瘤来源的循环肿瘤 DNA (ctDNA)。重要的是，ctDNA 检测可以作为组织活检或肿瘤生物标志物的补充，特别是在临床上难以获得肿瘤活检的情况下。在这里，我们介绍了基于 cfDNA 的液体活检中使用的最新技术，并回顾了 ctDNA 在癌症筛查、微小残留病检测、分子靶向药物选择、以及监测治疗反应。我们还讨论了临床环境中液体活检实施的挑战和未来前景。