Alpha-Fetoprotein (AFP)

AFP is a protein that the liver makes when its cells are growing and dividing to make new cells. AFP is normally high in unborn babies. After birth, AFP levels drop very low. Healthy children and adults who aren't pregnant have very little AFP in their blood.

If you aren't pregnant, AFP is mainly measured as a tumor marker. Tumor markers are substances that are often made by cancer cells or by normal cells in response to cancer. High levels of AFP can be a sign of cancer of the liver, ovaries or testicles. AFP goes up in roughly 7 out of 10 people with primary liver cancer (hepatocellular carcinoma) and in many people with certain testicular cancers (nonseminomatous germ cell tumors). It is not useful for pure seminomas of the testicle or dysgerminomas of the ovary.

AFP can also be mildly raised in some non-cancer liver conditions, such as viral hepatitis or cirrhosis, so a higher result on its own does not mean cancer.

An AFP tumor marker test cannot be used by itself to screen for or diagnose cancer, and it isn't recommended as a general screening test for cancer in people without symptoms or risk factors.

If you haven't been diagnosed with cancer, test results that show high levels of AFP may be a sign of cancer of the liver, ovaries, or testicles. AFP is most often raised in primary liver cancer (hepatocellular carcinoma) and in certain testicular cancers known as nonseminomatous germ cell tumors. But having a high AFP level doesn't mean you have cancer or that you will get cancer. Normal levels of AFP mean you're less likely to have a cancer that causes high AFP levels. But a normal test result doesn't rule out cancer because some people with these cancers have normal AFP levels.

If you're being treated for a cancer that increased your AFP levels, increasing AFP levels may mean that your treatment isn't working. Decreasing AFP levels may mean your treatment is working. AFP levels that have stayed the same may mean your disease is stable and hasn't gotten better or worse.

If you've finished treatment for cancer that caused high AFP levels, AFP levels that aren't normal may mean that you still have some cancer in your body. AFP levels that are higher now than they were shortly after treatment may mean your cancer is growing again.

If you have a long-lasting liver disease that's not cancer, you may need other tests to check for liver cancer if your test results show a sudden increase in AFP or your level is very high.