Cell growth within the body is tightly regulated by a number of factors. Cells that become mutated are normal signaled by the body to undergo cellular suicide to prevent the development of diseases such as cancer. Cancer occurs when cells have become mutated to the point that they become unresponsive to these signals from the body, and instead begin to divide uncontrollably, eventually forming a tumor. Several tools for cancer, such as tissue biopsies, can be uncomfortable for the patient. Screening for cancer markers in the blood is convenient and painless, and it allows for accurate detection of some forms of cancer.
CA-125
Ovarian cancer can be identified by testing for the presence of the CA-125 protein in the blood. Cancer Antigen 125, a protein found in large amounts on the surface of ovarian cancer cells, gets released into the bloodstream and circulates throughout the body.
According to Johns Hopkins, the CA-125 test can be taken once to check CA-125 levels at one time point, or as a series of blood samples taken at different time points to track CA-125 changes over time. A series of CA-125 tests can very accurately screen for ovarian cancer--99.7 percent of patients with positive serial CA-125 test results were found to have ovarian cancer. The CA-125 blood test may be done in combination with other diagnostic tests to identify cases of ovarian cancer.
Carcinoembryonic Antigen
Carcinoembryonic Antigen, also called CEA, is a protein found in high amounts on the surface of some cancer cells, which gets secreted into the blood. A CEA blood test can predict the presence of colon and rectal cancers, as well as cancers of the breast, pancreas, ovaries and lungs. The test simply involves taking blood from the patient and checking the level of CEA.
New York University reports that CEA testing may be done before and after surgery to remove tumors, during courses of chemotherapy or radiotherapy, or after cancer remission for early detection of cancer recurrence.
Prostate Specific Antigen
Prostate specific antigen, or PSA, is a protein that is expressed in prostate cells, which can be used to detect prostate cancer. Under normal conditions, little to no PSA is found in the blood. In prostate cancer, the prostate becomes damaged and PSA is secreted into the blood at high levels. A high level of PSA can indicate benign or cancerous growths on the prostate. A number of other factors, such as sexual activity, can also elevate PSA, so a high PSA level in the blood alone is not sufficient prostate cancer.
The University of Cincinnati reports that PSA testing may be used as a method for early detection of prostate cancer, to indicate a need for further cancer testing. Additionally, PSA testing may be used following prostate cancer therapy, or after cancer remission to detect possible recurrence.
