During fetal development, certain proteins are produced by the developing embryonic tissues that support the function, growth, and development of the organism. These proteins are later replaced by the proteins that continue to play specific structural or transport roles through the adult life or the organism or individual.
Occasionally, tumor cells develop that begin to produce these proteins that are associated with fetal development, referred to as oncofetal antigens. The most widely studied oncofetal antigens are:
- Alpha fetoprotein (AFP)
- Carcinoembryonic antigen (CEA)
Both of these tumor markers will be described in greater detail on the subsequent pages.