[A carbohydrate antigenic moiety that consists of proteins with sialylated lacto-N-fucopentose II decoration. Cancer antigen 19-9 (CA 19-9) is a protein that exists on the surface of tumor cells, and is cleaved in a process called tumor shedding. Clinically, it is a useful protein marker that is used to follow the course of persons with cancer; and is especially utilized in advanced pancreatic cancers. ( NCI )] (UMLS (NCI) C0006613) =Carbohydrate; Immunologic Factor ;