This review discusses the clinical applications of liquid biopsy in cancer screening, monitoring, and treatment. Liquid biopsy is a minimally invasive, real-time detection tool that analyzes tumor-derived components from body fluids such as blood, urine, or cerebrospinal fluid. It includes components like circulating tumor cells (CTCs), circulating tumor DNA (ctDNA), and extracellular vesicles (EVs). The review highlights the advantages of liquid biopsy over traditional tissue biopsies, such as noninvasiveness and the ability to monitor tumor progression and treatment response. **Cancer Screening:** Liquid biopsy offers a promising and evolving approach for early cancer detection. It can detect cancer at an earlier stage, improving patient outcomes and reducing the need for invasive procedures. CTCs and ctDNA are particularly useful in screening for various cancers, including lung, breast, and colorectal cancer. Studies have shown that CTCs and ctDNA levels can be used to predict tumor progression and recurrence, providing valuable information for early intervention. **Tumor Monitoring:** Liquid biopsy is effective in monitoring tumor progression and recurrence. CTCs and ctDNA levels correlate with tumor burden and can predict treatment response. For example, CTCs have been validated as a prognostic marker in various cancers, including esophageal, colorectal, and genitourinary cancers. ctDNA levels in plasma samples have also been linked to tumor volume and treatment efficacy, allowing for early assessment of treatment outcomes. **Tumor Treatment:** Liquid biopsy plays a crucial role in personalized medicine and targeted therapy. PD-L1 expression on CTCs is a key biomarker for predicting prognosis and response to immunotherapy. MSI status, detected in ctDNA, can predict the effectiveness of immunotherapy. Tumor mutation burden (TMB) and total tumor mutational burden (tTMB) are also valuable in predicting treatment outcomes, particularly in non-small cell lung cancer (NSCLC) treated with immunotherapy. The review emphasizes the potential of liquid biopsy in advancing cancer diagnosis, prognosis, and treatment, highlighting its advantages over traditional tissue biopsies. However, it also notes the challenges in standardizing detection methods and the need for further research to optimize clinical applications.This review discusses the clinical applications of liquid biopsy in cancer screening, monitoring, and treatment. Liquid biopsy is a minimally invasive, real-time detection tool that analyzes tumor-derived components from body fluids such as blood, urine, or cerebrospinal fluid. It includes components like circulating tumor cells (CTCs), circulating tumor DNA (ctDNA), and extracellular vesicles (EVs). The review highlights the advantages of liquid biopsy over traditional tissue biopsies, such as noninvasiveness and the ability to monitor tumor progression and treatment response. **Cancer Screening:** Liquid biopsy offers a promising and evolving approach for early cancer detection. It can detect cancer at an earlier stage, improving patient outcomes and reducing the need for invasive procedures. CTCs and ctDNA are particularly useful in screening for various cancers, including lung, breast, and colorectal cancer. Studies have shown that CTCs and ctDNA levels can be used to predict tumor progression and recurrence, providing valuable information for early intervention. **Tumor Monitoring:** Liquid biopsy is effective in monitoring tumor progression and recurrence. CTCs and ctDNA levels correlate with tumor burden and can predict treatment response. For example, CTCs have been validated as a prognostic marker in various cancers, including esophageal, colorectal, and genitourinary cancers. ctDNA levels in plasma samples have also been linked to tumor volume and treatment efficacy, allowing for early assessment of treatment outcomes. **Tumor Treatment:** Liquid biopsy plays a crucial role in personalized medicine and targeted therapy. PD-L1 expression on CTCs is a key biomarker for predicting prognosis and response to immunotherapy. MSI status, detected in ctDNA, can predict the effectiveness of immunotherapy. Tumor mutation burden (TMB) and total tumor mutational burden (tTMB) are also valuable in predicting treatment outcomes, particularly in non-small cell lung cancer (NSCLC) treated with immunotherapy. The review emphasizes the potential of liquid biopsy in advancing cancer diagnosis, prognosis, and treatment, highlighting its advantages over traditional tissue biopsies. However, it also notes the challenges in standardizing detection methods and the need for further research to optimize clinical applications.