tumor marker

Blood tests can be done to check for a substance called AFP (alpha-fetoprotein). People with liver cancer often have high AFP levels. Doctors also can compare the AFP levels before and after treatment to see how well the treatment is working.

(source: cancer.org)

The carcinoembryonic antigen (CEA) test measures the amount of this protein that may appear in the blood of some people who have certain kinds of cancers, especially cancer of the large intestine (colon and rectal cancer). It may also be present in people with cancer of the pancreas, breast, ovary, or lung.

(source: webmd.com)

PSA: prostate specific antigen