Metastasis is the leading cause of cancer-related death in patients with solid tumours. Current imaging technologies are not sufficiently sensitive to detect minimal residual disease (MRD; also known as measurable or molecular residual disease) after initial surgery or chemotherapy, pointing to the need for more sensitive tests to detect remaining traces of cancer in the body. Liquid biopsy, or the analysis of tumour-derived or tumour-induced cells or cellular products in the blood or other body fluids, has opened a new diagnostic avenue to detect and monitor MRD. Liquid biopsy is already used in clinical decision making for patients with haematological malignancies. Here, we review current knowledge on the use of circulating tumour DNA (ctDNA) to detect and monitor MRD in patients with solid tumours. We also discuss how ctDNA-guided MRD detection and characterization could herald a new era of novel ‘post-adjuvant therapies’ with the potential to eliminate MRD and cure patients before terminal metastatic disease is evident on imaging.

转移是实体瘤患者癌症相关死亡的主要原因。目前的成像技术不够灵敏，无法在初次手术或化疗后检测出微小残留病 （MRD;也称为可测量或分子残留病），这表明需要更灵敏的测试来检测体内残留的癌症痕迹。液体活检，或对血液或其他体液中肿瘤衍生或肿瘤诱导的细胞或细胞产物的分析，为检测和监测 MRD 开辟了一条新的诊断途径。液体活检已用于血液系统恶性肿瘤患者的临床决策。在这里，我们回顾了目前关于使用循环肿瘤 DNA （ctDNA） 检测和监测实体瘤患者 MRD 的知识。我们还讨论了 ctDNA 引导的 MRD 检测和表征如何预示着新型“辅助治疗”的新时代，有可能在影像学上明显出现晚期转移性疾病之前消除 MRD 并治愈患者。