In detail, the serum levels of 4 glycoforms (GN2F2 at N184, G-N&G2S2, G2&G3NFS and G2N3F at N207/N211), and tumor markers CEA and CA153 were increased in breast cancer, while the serum levels of 3 glycoforms (G6N3F6, GN2FS at N184, GN3 at N207/N211) were decreased in breast cancer, when compared to benign breast diseases. Here, CEACAM5 is linked to breast cancer.