A number of different types and forms of cancer biomarkers (tumor markers) exist. These markers include hormones, as well as different functional subgroups of proteins such as enzymes, glycoproteins, oncofetal antigens and receptors. Furthermore, other changes in tumors, such as genetic mutations, amplifications or translocations, and changes in microarray-generated profiles (genetic signatures), are also types of cancer biomarkers (tumor markers). Cancer biomarkers can be functionally classified into several types, such as diagnostic (screening) biomarker, prognostic biomarker, stratification (predictive) biomarker, and so on.
Regardless of the type of cancer biomarker (tumor marker) or profile, the use of a tumor marker must be associated with proven improvements in patient outcomes, such as increased survival or enhanced quality of life, in order to be substantiated.