What is an Alpha-Fetoprotein (AFP) Tumor Marker Test?

March 28, 2019

Tumor markers are substances in the human body that are produced by tumors and secreted into the blood, urine, or other bodily fluids. Certain benign conditions can also raise these markers, but significant elevations or a progressive rise can indicate a malignant process. 

An AFP, or alpha-fetoprotein, tumor marker test—one of many different types of tumor marker tests—can help detect and screen for certain kinds of cancer, including liver cancers or germ cell tumors. 

What is AFP?

AFP is a protein that is typically produced by the fetal liver and yolk sac.  Therefore, all newborns have an elevated AFP level and levels must be interpreted with caution in young babies when evaluating for an AFP-secreting malignancy. 

After birth, a person’s AFP levels begin to decrease significantly as they approach the age of one. By the time they are an adult, their levels should be very low. Therefore, an elevated AFP in an older individual can often raise cause for concern.

parts of the body where extragonadal germ cell tumors may form, including the pineal gland in the brain, the mediastinum (the area between the lungs), and the retroperitoneum (the area behind the abdominal organs). Source: National Cancer Institute.
Parts of the body where extragonadal germ cell tumors may form, including the pineal gland in the brain, the mediastinum (the area between the lungs), and the retroperitoneum (the area behind the abdominal organs). Source: National Cancer Institute.

Who needs an AFP test?

Your physician might order an AFP level if he/she is concerned that you have a type of tumor that normally secretes AFP, such as a liver or germ cell tumor.

What does it mean if my AFP levels are higher than normal?

If an AFP is elevated, it usually requires that follow-up studies are performed. To obtain a definitive diagnosis, a patient should undergo blood tests, imaging tests, and/or a biopsy to determine whether an AFP-secreting tumor is present.

Managing cancer with AFP tumor marker testing

Even though AFP tumor marker testing isn’t perfect in diagnosing cancer, it can be extremely useful for those already diagnosed with cancer. Doctors can determine if a patient’s treatment is working by consistently monitoring the levels of AFP during the treatment period. If a patient’s AFP level begins to decrease after treatment, it’s a good sign that the treatment is effective. AFP can also be a useful tool to determine whether a patient remains in remission following completion of therapy.