Recurrence and metastasis remain the main causes of mortality in patients with solid tumors after curative treatment, largely driven by clinically undetectable minimal residual disease (MRD). Conventional imaging and serum biomarkers lack sufficient sensitivity and specificity for MRD detection, leading to delayed or passive clinical decision-making. Advances in circulating tumor DNA (ctDNA)-based liquid biopsy technology now enable highly sensitive and real-time monitoring of MRD.This study proposes a ctDNA-guided " monitoring-intervention" closed-loop clinical management model for solid tumors. The model integrates sequential processes encompassing postoperative MRD baseline assessment, recurrence risk stratification, early molecular warning, therapeutic intervention selection, and longitudinal efficacy evaluation. We analyze the core technological platforms supporting this framework, compare the strengths and limitations of different ctDNA detection strategies and outline system architecture and implementation approaches for the closed-loop model.Using colorectal and lung cancers as representative examples, this paper comprehensively reviews the supporting clinical evidence, ongoing controversies, and major challenges in translating this model into clinical practice. Furthermore, we provide forward-looking perspectives on standardizing key technologies, enriching clinical data, assessing cost-effectiveness, and developing intelligent decision-making systems to enable personalized, dynamic, and prospective precision treatment for solid malignancies.