The low sensitivity of immunoassays for quantifying known cancer antigens hinders the discovery of biomarkers for early cancer detection. Highly sensitive R&D immunoassays are not as reliable as FDA-approved ones. We define the diagnostic biomarker as a protein whose structure is altered in the presence of a given pathology, resulting in changes in the nature or 3D arrangement of the solvent-exposed groups or interactions of the protein with other proteins.

The discovery of such protein biomarkers with solvent interaction analysis (SIA) technology will be described. One example of this technology's application is the new commercially available isoPSA test. The preliminary results of the technology's application for early detection of breast cancer will be presented.