CPTAC

The discovery of protein biomarkers of disease has been hindered by the complexity of plasma, the liquid portion of blood. Human plasma contains hundreds of thousands of different proteins that are present at levels spanning ten orders of magnitude. While much is known about the most abundant of these proteins, our knowledge of the remainder — perhaps as much as 98% of all plasma proteins — remains decidedly incomplete. And it is within this lower range that most disease-specific biomarkers will likely fall.

Biomarkers are important clinical tools for cancer screening and diagnosis and also can be used by doctors to tailor patients’ treatments. But the “gold standard” — a protein biomarker or set of biomarkers that identifies patients with cancer from a simple blood test — has proven elusive for most forms of the disease.