Tumor markers are substances, usually proteins, that are produced by the body in response to cancer growth. Some markers are specific to one type of cancer, while others can be seen in several cancer types.
Measurements of tumor marker levels can be useful, when used with other tests, in the detection and diagnosis of some types of cancer. However, tumor marker levels alone are not sufficient for diagnosis.
Tumor markers have many uses:
screening for cancer presence, making a diagnosis of cancer, determining the status of the cancer, evaluating the success of different treatments in controlling cancer, and monitoring the health of a patient in remission.
Prostate Specific Antigen : Can be elevated in the presence of prostate cancer. An elevated PSA may also be a signal of other non-cancerous diseases such as benign prostatic hyperplasia (BPH) or prostatitis.
Carbohydrate Antigen 125 (CA-125): Elevated levels seen in patients with ovarian cancer. It is sometimes elevated in the presence of other cancers. Also, many non-cancerous conditions elevate this marker, such as endometriosis and liver disease.
CA 15-3:These markers are useful in following the course of breast cancer.
CA 19-9: Is commonly used as a check for the spread of pancreatic cancer. It
is also elevated in patients with colorectal and stomach cancer. There are non-cancerous conditions such as gallstones and cirrhosis that can elevate CA 19-9.
Carcinoembryonic Antigen (CEA): primarily used in monitoring colorectal cancer, especially when the disease has spread. Elevated levels can also occur in patients with non-cancerous conditions including pancreatitis and liver disease.
Alpha-Fetoprotein (AFP):normally produced by a developing fetus, but levels decrease soon after birth. An elevated AFP level strongly suggests the presence of either primary liver cancer or germ cell cancer of the ovary or testicle.
Human Chorionic Gonadotropin (HCG):normally produced by the placenta during pregnancy. It is also used to screen for a rare cancer of the uterus and to monitor the treatment of trophoblastic disease. Elevated HCG levels may also indicate the presence of cancers of the testis, ovary, liver, stomach, pancreas and lung.