[Research Advances in ctDNA-MRD Monitoring in Local Treatment 
for Non-small Cell Lung Cancer]

Non-small cell lung cancer (NSCLC) remains at risk of recurrence after local treatment, and early identification of molecular residual disease before radiological progression is an important issue in risk stratification. Circulating tumor DNA (ctDNA)-based molecular residual disease (MRD) monitoring provides a promising molecular tool for recurrence risk assessment, response evaluation, and subsequent treatment stratification. However, surgery, thermal ablation, definitive chemoradiotherapy, and stereotactic body radiotherapy differ in tumor burden changes, tissue injury, and DNA release and clearance, leading to uncertainty regarding sampling time points, result interpretation, and clinical utility. This review summarizes recent advances in ctDNA-MRD monitoring after local treatment for NSCLC, focusing on ctDNA kinetics, candidate assessment windows, assay platform differences, prognostic value, and translational limitations in perioperative, thermal ablation, and radiotherapy settings. Current evidence suggests that perioperative ctDNA-MRD status is associated with pathological response, recurrence risk, and survival outcomes. In contrast, direct evidence after thermal ablation and stereotactic body radiotherapy remains limited, and proposed sampling time points should be regarded as candidate assessment windows rather than standardized recommendations. Further studies with standardized sampling, assay validation, and prospective interventional designs are needed to clarify the clinical value of ctDNA-MRD in adjuvant treatment selection, intensified surveillance, and individualized management.
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