Which antigen is considered an oncofetal antigen?

Which antigen is considered an oncofetal antigen?

• A. AFP
• B. CA-125
• C. β-hCG
• D. PSA

Answer: (A)

Oncofetal antigens are proteins produced during fetal life that can be reexpressed by certain cancers. Alpha-fetoprotein is made by the fetal liver and yolk sac, and after birth its levels drop. When tumors such as hepatocellular carcinoma or some germ cell tumors recur this fetal program can be reactivated, causing AFP to be produced again. This reexpression pattern is the hallmark of an oncofetal antigen, making AFP a classic example. The other markers have different roles: CA-125 is linked to ovarian cancer but is not a fetal protein; β-hCG is a pregnancy hormone produced by placental tissue (and in some cases elevated in tumors) rather than a fetal antigen; PSA is prostate-specific and not related to fetal expression.

Oncofetal antigens are proteins produced during fetal life that can be reexpressed by certain cancers. Alpha-fetoprotein is made by the fetal liver and yolk sac, and after birth its levels drop. When tumors such as hepatocellular carcinoma or some germ cell tumors recur this fetal program can be reactivated, causing AFP to be produced again. This reexpression pattern is the hallmark of an oncofetal antigen, making AFP a classic example. The other markers have different roles: CA-125 is linked to ovarian cancer but is not a fetal protein; β-hCG is a pregnancy hormone produced by placental tissue (and in some cases elevated in tumors) rather than a fetal antigen; PSA is prostate-specific and not related to fetal expression.