It has been known for a number of decades that changes in the level of circulatory ST6Gal-1 and the circulatory sialyl-glycan structures constructed by ST6Gal-1 are associated with a diverse array of clinical conditions including stress (6), atherosclerosis (4, 7), alcoholism (8, 9), as well as certain cancers, particularly colon and breast cancers, and multiple myeloma (10–12). This evidence concerns the gene ST6GAL1 and breast cancer.