Tumor markers are substances that help us determine the presence of certain cancers. Their concentrations are evaluated in venous blood or in other body fluids (for example CA 19-9 in a sample of fluid obtained from a pancreatic cyst).
The use of tumor markers has been a brilliant idea. Given that the malignant diseases are very dreaded, we pay a great effort to understand them and improve early diagnosis and effective treatment. The therapy and prognosis depend mainly on the early detection. However, the diagnosis is usually not easy as the early stages of tumors have no symptoms. Therefore a question has occurred - would it be possible to diagnose a tumor from a blood sample? And it has been confirmed that it is possible, but only to some extent. Serum concentration of certain substances may increase when a certain tumor is present and such substances have been called tumor markers.
Substances known as tumor markers are present in the body of each of us, but usually in minimal concentrations. It is their increased concentration, what worries us and not their mere presence.
Tumor markers are generally not very reliable. It can easily happen that a person with cancer has normal value of all tumor markers and vice versa, particular tumor markers may be elevated in many non-malignant diseases (inflammatory processes, liver cirrhosis, benign tumors, etc.). Therefore, tumor markers are only auxiliary in diagnostics of tumor and they are much more valuable in evaluation of therapy effectiveness of an already known cancer (see below).
The increase of concentration of the relevant tumor marker in blood is usually directly proportional to the number of tumor cells in the body. When the treatment starts (surgery, radiation, chemotherapy), the value of the tumor marker should decrease. Regular monitoring of the tumor marker may say, if the therapy has been successful (low concentration of the marker) or if there is high-risk of the tumor's recurrence (elevation of previously low tumor marker).
Well-known tumor markers
This is the abbreviation of prostate-specific antigen. This compound is produced by prostatic cells and its concentration elevates in prostate cancer, benign enlargement of prostate and in prostatitis.
AFP means alpha-fetoprotein. It is associated with liver cancer and it may be increased by some rare germ cell tumors. If we find an unknown liver focus, it is advisable to evaluate the serum concentration of AFP.
This tumor marker is typically increased certain forms of breast cancer.
The abbreviation hCG means human chorionic gonadotropin. The compound is normally elevated in pregnant women and in patients with a very aggressive (but well responding to therapy) tumor known as choriocarcinoma.