癌症是影响人类寿命的主因之一。与临床上常用的组织活检技术相比，液体活检作为癌症的一种检测手段，具有非侵入性、准确性高、取样简便、价格低廉等多种显著优势。液体活检在多种癌症，包括肺癌、宫颈癌、前列腺癌等的早期检测、动态监测和靶向治疗上均表现出很大的潜力，为癌症的检测和治疗提供了新的技术手段和研究思路。液体活检常常采用循环肿瘤DNA、循环肿瘤细胞和外泌体作为检测癌症病程的标志物，以PCR、NGS、ELISA等生命科学研究中常用的技术为基础方法，利用多种指标作为评判癌症病程的依据。文章综述了循环肿瘤DNA、循环肿瘤细胞和外泌体作为肿瘤液体活检标志物的检测原理，以及它们在临床应用方面近5年的研究进展。

Cancer is one of the main factors threatening human life. Compared with the commonly used tissue biopsy technology, liquid biopsy, as a detection method of cancer, has many significant advantages, such as non-invasive, high accuracy, simple sampling
and low price. Liquid biopsy has great potential in early detection, dynamic monitoring and targeted treatment of various cancers,
including lung cancer, cervical cancer and prostate cancer. It provides a new technical means and research ideas for cancer detection and treatment. In liquid biopsy, circulating tumor DNA (ctDNA), circulating tumor cell (CTC) and exosomes are often used as markers to detect the course of cancer. Based on the techniques commonly used in life science research such as PCR, NGS and ELISA, a variety of indicators are used as the basis to judge the course of cancer. In this paper, the detection principle of ctDNA, CTC and exosomes as liquid biopsy markers and their recent research progress in clinical application are reviewed.