Laboratory Tests - Types

Tumor Markers

Tumor markers are substances either released by cancer cells into the blood or urine or substances created by the body in response to cancer cells. Tumor markers are used to evaluate how well a patient has responded to treatment and to check for tumor recurrence. Research is currently being conducted on the role of tumor markers in detection, diagnosis, and treatment of cancers.

According to the National Cancer Institute (NCI), tumor markers are useful in identifying potential problems, but they must be used with other tests for the following reasons:

• People with benign conditions may also have elevated levels of these substances in their blood.
• Not every person with a tumor has tumor markers.
• Some tumor markers are not specific to any one type of tumor.

The following is a brief description of some of the more useful tumor markers:

• Prostate-Specific Antigen (PSA)
  Prostate-specific antigen is always present in low concentrations in the blood of adult males. An elevated PSA level in the blood may indicate prostate cancer, but other conditions such as benign prostatic hyperplasia (BPH) and prostatitis can also raise PSA levels. PSA levels are used to evaluate how a patient has responded to treatment and to check for tumor recurrence.
• Prostatic Acid Phosphatase (PAP)
  PAP originates in the prostate and is normally present in small amounts in the blood. In addition to prostate cancer, elevated levels of PAP may indicate testicular cancer, leukemia, and non-Hodgkin’s lymphoma, as well as some noncancerous conditions.
• CA 125
  Ovarian cancer is the most common cause of elevated CA 125, but cancers of the uterus, cervix, pancreas, liver, colon, breast, lung, and digestive tract can also raise CA 125 levels. Several noncancerous conditions can also elevate CA 125. CA 125 is mainly used to monitor the treatment of ovarian cancer.
• Carcinoembryonic Antigen (CEA)
  CEA is normally found in small amounts in the blood. Colorectal cancer is the most common cancer that raises this tumor marker. Several other cancers can also raise levels of carcinoembryonic antigen.
• Alpha-Fetoprotein (AFP)
  Alpha-fetoprotein is normally elevated in pregnant women since it is produced by the fetus. However, AFP is not usually found in the blood of adults. In men, and in women who are not pregnant, an elevated level of AFP may indicate liver cancer or cancer of the ovary or testicle. Noncancerous conditions may also cause elevated AFP levels.
• Human Chorionic Gonadotropin (HCG)
  HCG is another substance that appears normally in pregnancy and is produced by the placenta. If pregnancy is ruled out, HCG may indicate cancer in the testis, ovary, liver, stomach, pancreas, and lung. Marijuana use can also raise HCG levels.
• CA 19-9
  This marker is associated with cancers in the colon, stomach, and bile duct. Elevated levels of CA 19-9 may indicate advanced cancer in the pancreas, but it is also associated with noncancerous conditions, including gallstones, pancreatitis, cirrhosis of the liver, and cholecystitis.
• CA 15-3
  This marker is most useful in evaluating the effect of treatment for women with advanced breast cancer. Elevated levels of CA 15-3 are also associated with cancers of the ovary, lung, and prostate, as well as noncancerous conditions such as benign breast or ovarian disease, endometriosis, pelvic inflammatory disease, and hepatitis. Pregnancy and lactation also can raise CA 15-3 levels.
• CA 27-29
  This marker, like CA 15-3, is used to follow the course of treatment in women with advanced breast cancer. Cancers of the colon, stomach, kidney, lung, ovary, pancreas, uterus, and liver may also raise CA 27-29 levels. Noncancerous conditions associated with this substance are first trimester pregnancy, endometriosis, ovarian cysts, benign breast disease, kidney disease, and liver disease.
• Lactate Dehydrogenase (LDH)
  LDH is a protein that normally appears throughout the body in small amounts. Many cancers can raise LDH levels, so it is not useful in identifying a specific kind of cancer. Measuring LDH levels can be helpful in monitoring treatment for cancer. Noncancerous conditions that can raise LDH levels include heart failure, hypothyroidism, anemia, and lung or liver disease.
• Neuron-Specific Enolase (NSE)
  NSE is associated with several cancers, but it is used most often to monitor treatment in patients with neuroblastoma or small cell lung cancer.