CEACAM5 and neoplasm: Liquid biopsy is an effective noninvasive examination method in diagnosis and monitoring of tumors, which contains a variety of tumor-derived materials, such as protein, circulating DNA, circulating RNA, circulating tumor cells, extracellular vesicles, etc. However, the clinical value of commonly used liquid biopsy tumor biomarkers, including carbohydrate antigen 153 (CA153) and carcinoembryonic antigen (CEA), is better reflected in the dynamic monitoring of therapeutic effects in patients with BC rather than screening and diagnosis of BC [4,5].