Since the glycosylation of proteins is known to change in tumor cells during the development of breast cancer, a glycomic approach is being used here to find relevant biomarkers of breast cancer. These glycosylation changes are known to correlate with increasing tumor burden and poor prognosis. Current antibody-based immunochemical tests for cancer biomarkers of ovarian (CA125), breast (CA 27.29 or CA15-3), pancreatic, gastric, colonic and ovarian carcinoma (CA19-9), target highly glycosylated mucin proteins. However, these tests lack the specificity and sensitivity for use in early detection. This glycomics approach to find glycan biomarkers of breast cancer involves chemically cleaving oligosaccharides (glycans) from glycosylated proteins that are shed or secreted by breast cancer tumor cell lines. The resulting free glycan species are analyzed by matrix-assisted laser desorption/ionization (MALDI) Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS). Further structural analysis of the glycans can be performed in FTMS through the use of tandem mass spectrometry with infrared multi-photon dissociation (IRMPD). Glycan profiles were generated for each cell line and compared. These methods were then used to analyze sera obtained from a mouse model of breast cancer, and a small number of serum samples obtained from human patients diagnosed with breast cancer, or patients with no known history of breast cancer. In addition to the glycosylation changes detected in mice as mouse mammary tumors developed, glycosylation profiles were found to be sufficiently different so as to distinguish patients with cancer from those without. Although the small number of patient samples analyzed so far is inadequate to make any legitimate claims at this time, these promising, but very preliminary results suggest that glycan profiles may contain distinct glycan biomarkers that may correspond to glycan "signatures of cancer".