The Alpha Feto Protein (AFP) test is used as a cancer marker to detect elevated levels of AFP in the blood, which can indicate the presence of certain cancers, particularly liver cancer (hepatocellular carcinoma). Elevated AFP levels can also be seen in germ cell tumors, testicular cancer, and some other cancers. Additionally, AFP is used in prenatal screening to assess the risk of fetal abnormalities. A blood sample is required for this test. Elevated levels in adults often prompt further investigation to identify and monitor cancer or liver disease.