结直肠癌是我国常见恶性肿瘤之一，疾病负担较重。受早期筛查不足等因素影响，部分患者确诊时已处于中晚期，预后改善仍面临较大挑战。液体活检以血液等体液为样本，通过检测循环肿瘤细胞（CTCs）、循环肿瘤DNA（ctDNA）及肿瘤教化血小板（TEPs）等主要生物标志物，可在一定程度上动态反映肿瘤相关分子特征。现阶段，液体活检更适合作为结肠镜的补充工具，主要应用于筛查分流、术后微小残留病灶监测和复发风险评估，尚不能替代结肠镜。现有证据显示，ctDNA研究基础相对较好，在微小残留病灶监测和辅助治疗决策方面最接近临床应用；CTCs可提供细胞形态和部分功能信息，但受低丰度、高异质性及检测标准不统一等因素影响，临床推广仍受限；TEPs取样方便、RNA信息较丰富，但相关证据仍需进一步积累。未来仍需围绕提高早期检出率、统一检测流程、控制检测成本和加强前瞻性研究等方面推进，并进一步明确其在不同临床场景中的应用价值。

Colorectal cancer remains one of the most common malignancies in China and continues to impose a heavy disease burden. Because early screening is still insufficient in some populations, a proportion of patients are already at an advanced stage at diagnosis, and further improving prognosis remains difficult. Liquid biopsy uses blood or other body fluid samples to detect tumor-related information, mainly through biomarkers such as circulating tumor cells (CTCs), circulating tumor DNA (ctDNA), and tumor-educated platelets (TEPs). At the current stage, liquid biopsy should be viewed more as a useful supplement to colonoscopy rather than as a replacement. Clinically, liquid biopsy may find applications in screening triage, postoperative monitoring of minimal residual disease, and recurrence risk assessment. Among the circulating biomarkers, ctDNA is supported by more robust evidence and is closer to clinical translation, particularly in minimal residual disease detection and adjuvant treatment decision-making. CTCs can offer cellular-level information on tumour morphology and function, but their clinical use remains constrained by low abundance, pronounced heterogeneity, and a lack of assay standardisation. Tumour-educated platelets are readily accessible and carry abundant RNA-related information; however, their clinical value still awaits confirmation in larger, well-designed studies. Future efforts should prioritise improving the sensitivity of early detection, establishing standardised testing workflows, reducing costs, and conducting prospective investigations, so that the role of liquid biopsy can be more clearly delineated across different clinical scenarios.