Merck Manual

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Some Tumor Markers*

Some Tumor Markers*

Tumor Marker


Comment About Testing

Alpha-fetoprotein (AFP)

Elevated AFP levels often are found in the blood of people with liver cancer ( hepatocellular carcinoma Hepatocellular Carcinoma Hepatocellular carcinoma is a cancer that begins in the liver cells and is the most common of the primary liver cancers. Having hepatitis B or hepatitis C or fatty liver disease, or drinking... read more ). In addition, elevated AFP is often found in people with certain cancers of the ovary or testis.

Testing can be useful in monitoring treatment and perhaps for diagnosis of cancer in a person with cirrhosis (liver damage due to alcohol or viral hepatitis).

Beta-human chorionic gonadotropin (ß-HCG)

Testing can be useful in diagnosing such cancers and in monitoring treatment.


This test is not recommended for cancer screening.


This test may be used to detect the presence of cancer and monitor response to treatment of medullary thyroid cancer.

Carbohydrate antigen 125 (CA-125)

This test is not recommended for cancer screening.

Carbohydrate antigen 19-9 (CA 19-9)

This test is used in monitoring response to treatment and in the diagnosis of tumors of unknown origin.

Carbohydrate antigen 27.29 (CA27.29)

This test can be used in monitoring treatment.

Carcinoembryonic antigen (CEA)

Levels may be elevated in the blood of people with colon cancer Colorectal Cancer Family history and some dietary factors (low fiber, high fat) increase a person’s risk of colorectal cancer. Typical symptoms include bleeding during a bowel movement, fatigue, and weakness... read more Colorectal Cancer . Blood levels may also be elevated in patients with other cancers or noncancerous inflammatory conditions.

After surgery for colon cancer, testing can be useful in monitoring treatment and detecting recurrence.

Prostate-specific antigen (PSA)

Levels are elevated in men with noncancerous (benign) enlargement of the prostate and often are considerably higher in men with prostate cancer Prostate Cancer Prostate cancer begins in a small area of the prostate gland, an organ found only in males. The risk of prostate cancer increases as men age. Symptoms, such as difficulty urinating, a need to... read more Prostate Cancer . Men with an elevated PSA level should be evaluated further by a doctor.

Testing may be useful in screening for cancer and is helpful in detecting recurrence after treatment.


This test is not recommended for routine screening but may be helpful for monitoring response to treatment of thyroid cancer.

* Because tumor markers can also be produced by noncancerous tissue, doctors generally do not use them to screen healthy people. Exceptions may include PSA for prostate cancer and AFP for people at risk of hepatoma. In families with inherited medullary thyroid cancer, a rare condition, levels of calcitonin in the blood also may be a useful screening test.