Circulating tumor DNA in neoadjuvant therapy for solid tumors.

Circulating tumor DNA (ctDNA), a core component of liquid biopsy, demonstrates significant potential in the field of neoadjuvant therapy for solid tumors. This review systematically examines the role of ctDNA across the pre-, intra-, and post-neoadjuvant treatment phases, with a focus on its value in predicting therapeutic efficacy, assessing early treatment response, detecting minimal residual disease (MRD), and monitoring for recurrence. By synthesizing the latest clinical research data and advancements in molecular detection technologies, this article aims to elucidate how ctDNA is facilitating a shift towards more precise, dynamic, and individualized paradigms in neoadjuvant therapy for solid tumors. Furthermore, it analyzes the current challenges and future directions for integrating ctDNA analysis into clinical practice to optimize patient management and outcomes. Throughout, clinically validated applications are explicitly distinguished from those that remain investigational, and key unresolved questions are highlighted.