Which of the following is an oncofetal antigen?

Which of the following is an oncofetal antigen?

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

Answer: (A)

Oncofetal antigens are proteins produced during fetal development that can be re-expressed by certain cancers, making them useful as tumor markers. Alpha-fetoprotein is a fetal protein produced by the liver and yolk sac; in adults it’s normally low, but it rises in hepatocellular carcinoma and some germ cell tumors. That re-expression in cancer fits the concept of an oncofetal antigen, which is why this option is the best one. The other markers are not classic oncofetal antigens: CA-125 is a marker linked to ovarian cancer without being a fetal protein, beta-hCG is a placental hormone (though it can be elevated in some germ cell tumors), and PSA is specific to the prostate.

Oncofetal antigens are proteins produced during fetal development that can be re-expressed by certain cancers, making them useful as tumor markers. Alpha-fetoprotein is a fetal protein produced by the liver and yolk sac; in adults it’s normally low, but it rises in hepatocellular carcinoma and some germ cell tumors. That re-expression in cancer fits the concept of an oncofetal antigen, which is why this option is the best one. The other markers are not classic oncofetal antigens: CA-125 is a marker linked to ovarian cancer without being a fetal protein, beta-hCG is a placental hormone (though it can be elevated in some germ cell tumors), and PSA is specific to the prostate.