Alpha-Fetoprotein (AFP) is a blood test that measures the amount of AFP circulating in your bloodstream. AFP is a protein made in large amounts by a developing fetus (mainly by the fetal liver and yolk sac). In healthy, non-pregnant adults, AFP is usually very low.

Because certain cancers can cause AFP to rise, AFP is commonly used as a tumor marker. A tumor marker is a substance that may be higher in the blood when some types of cancer are present or when cancer activity changes over time. AFP testing is most often used in oncology to help evaluate possible liver cancer (hepatocellular carcinoma) and to monitor treatment response or recurrence. It is also used for some germ cell tumors (tumors that start in reproductive cells), especially certain testicular and ovarian cancers.

How to understand results (plain language): A higher-than-normal AFP level can be a clue that a condition affecting the liver or certain tumors may be present, but it does not diagnose cancer by itself. AFP can also rise for non-cancer reasons (for example, chronic hepatitis or cirrhosis). Very high or steadily rising AFP levels are more concerning for active cancer in the right clinical setting. Falling AFP levels during treatment may suggest that treatment is working, while rising AFP levels after treatment may suggest tumor growth or recurrence. Your clinician will interpret AFP levels alongside your symptoms, imaging (such as ultrasound, CT, or MRI), and other lab tests that reflect hepatic function (liver health).

A clinician may order an AFP blood test for cancer evaluation, cancer monitoring, or liver-related risk assessment. It is commonly used in people with higher risk of hepatocellular carcinoma, particularly those with long-term liver disease.

AFP is usually done to:

Help evaluate possible liver cancer (hepatocellular carcinoma): If you have symptoms or imaging findings that raise concern for liver cancer—such as an unexplained liver mass on ultrasound, unexplained weight loss, persistent right upper abdominal pain, or worsening liver function—AFP may be ordered as part of a cancer diagnosis workup.

Screen or surveil high-risk patients: In many practices, AFP may be used along with periodic liver ultrasound for surveillance in people at increased risk for liver cancer, such as those with cirrhosis or chronic hepatitis B. (Specific surveillance plans vary by guideline and individual risk.)

Monitor known cancer over time (tumor monitoring): If you have been diagnosed with hepatocellular carcinoma or an AFP-producing germ cell tumor, AFP can be measured before treatment (to establish a baseline), during treatment (to assess response), and after treatment (to watch for recurrence). Trends across multiple tests are often more useful than a single value.

Evaluate suspected germ cell tumors: AFP is often ordered with other tumor markers (such as beta-hCG and LDH) when a testicular mass, ovarian mass, or certain symptoms suggest a germ cell tumor. These markers can help with diagnosis, staging, and monitoring after surgery or chemotherapy.

Important context: AFP can be elevated in non-cancer liver conditions (like hepatitis flares) and may be normal in some people who still have liver cancer. For that reason, AFP is not a stand-alone test; it is interpreted with imaging, physical exam, medical history, and other labs.

• Hepatocellular carcinoma (primary liver cancer)
• Germ cell tumors (including non-seminomatous testicular cancer and some ovarian germ cell tumors)
• Chronic hepatitis B and chronic hepatitis C
• Cirrhosis (scarring of the liver from long-term liver disease)
• Alcohol-associated liver disease
• Nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH)
• Other liver tumors or metastatic cancer involving the liver (in selected cases)
• Pregnancy-related AFP elevation (physiologic; interpreted differently in prenatal screening)

• Supporting liver cancer risk surveillance in people with chronic liver disease (often alongside imaging)
• Helping guide cancer diagnosis when a liver mass or suspicious symptoms are present
• Tracking tumor marker trends to monitor treatment response in hepatocellular carcinoma
• Detecting possible recurrence through ongoing tumor monitoring after cancer treatment
• Monitoring certain germ cell tumors in oncology care (baseline, response, and follow-up)
• Providing additional context about hepatic function and liver inflammation when interpreted with other liver tests (e.g., AST/ALT, bilirubin, INR)