小细胞肺癌（SCLC）具有高度侵袭性，预后不良。尽管 SCLC 中循环肿瘤 DNA (ctDNA) 相对普遍，但与非 SCLC 不同，目前尚未实施液体活检，其中血液中的无细胞 DNA (cfDNA) 突变分析可用于指导靶向治疗和评估微小残留病。 cfDNA 甲基化分析对于 SCLC 检测高度敏感，并有望用于疾病监测和分子分型； cfDNA 碎片分析也显示出临床潜力。染色体外 DNA (ecDNA) 经常在 SCLC 中观察到，可促进肿瘤异质性和化疗耐药性，并且可以在血液中检测到。我们讨论如何利用这些 cfDNA 分析模式来扩展 SCLC 液体活检的临床应用。版权所有 © 2024 作者。由爱思唯尔有限公司出版。保留所有权利。

Small cell lung cancer (SCLC) is highly aggressive with poor prognosis. Despite a relative prevalence of circulating tumour DNA (ctDNA) in SCLC, liquid biopsies are not currently implemented, unlike non-SCLC where cell-free DNA (cfDNA) mutation profiling in the blood has utility for guiding targeted therapies and assessing minimal residual disease. cfDNA methylation profiling is highly sensitive for SCLC detection and holds promise for disease monitoring and molecular subtyping; cfDNA fragmentation profiling has also demonstrated clinical potential. Extrachromosomal DNA (ecDNA), that is often observed in SCLC, promotes tumour heterogeneity and chemotherapy resistance and can be detected in blood. We discuss how these cfDNA profiling modalities can be harnessed to expand the clinical applications of liquid biopsy in SCLC.Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.