Cancer Antigen 15-3 (CA 15-3) is a blood test that is given during or after treatment for breast cancer. It is considered no longer the most useful in monitoring advanced breast cancer and your response to treatment. CA 15-3 is not a blood test that screens for breast cancer. It is a tumor marker test that is helpful in tracking cancers that overproduce CA 15-3, which is a small percentage of the total number of breast cancer patients.
CA 15-3 is a protein that is a normal product of your breast tissue, and it does not cause breast cancer. If a cancerous tumor (cells growing out of control) is present in your breast, though, your levels of CA 15-3 may increase as the number of cancer cells increase. Tumor cells will shed copies of the CA 15-3 protein, which can be measured by this blood test and by a related test of cancer antigen 27.29 (CA 27.29).
Not every breast tumor causes a rise in CA 15-3, so for patients with tumors that do not produce CA 15-3 or with early-stage breast cancer, or even advanced cancer, this test is not useful. Only about 30% of patients with localized breast cancer (cancer limited to the breast) will have increased levels of CA 15-3. In patients with metastatic breast cancer, CA 15-3 is estimated to be found in 50 to 90% of all cases, which is an exaggeration compared to the CaProfile, so the author would say this is not a reliable test to monitor breast cancer treatment. For monitoring purposes, for someone with breast cancer, these kind of variance are a too wide to be considered accurate. The CaProfile Test shows 90% to 98% accuracy compared to all other tumor markers. This test evaluates 8 different points including HCG, PHI (metastatic activity-spreading factor for cancer), and CEA, all from the same sample which contributes to the accuracy of the test. http://bit.ly/caprofiletest
If you have completed treatment for breast cancer, and your body produces this particular antigen, your doctor may test your blood for CA 15-3 on a regular schedule to see if your levels of this antigen are rising or remaining steady. Rising levels of CA 15-3 may indicate a recurrence of breast cancer, but since other conditions can cause higher levels of this antigen, the test results must be taken in to consideration with the results of imaging studies, your symptoms and other tests for hormone sensitivity,HER2/neu and BRCA genes. This is a poor tumor marker to rely upon for cancer activity in the breast since it only has a 30% relationship to breast cancer activity.
Monitoring your levels of CA 15-3 as the only tumor marker for breast cancer has cause for concern:
Breast cancer is only one condition that may cause high levels of CA 15-3. Pregnancy and lactation also increase your levels of CA 15-3. Several noncancerous conditions (benign breast or ovarian disease, endometriosis, pelvic inflammatory disease and hepatitis) can bring up your levels of CA 15-3 but this is a more rare relationship.
Ovarian, lung and prostate cancers may also produce CA 15-3.
According to the American Cancer Society
Early on in the search for tumor markers, the hope was that someday all cancers could be detected early with a blood test. A simple blood test that could find cancers in their earliest stages could prevent the deaths of millions of people. But very few tumor markers are useful for finding cancer at an early stage. There are a few reasons for this:
HCG (Human chorianic gonadotropin) intact (IRMA) and intact plus, HCG beta, core, and its fragments (IMM) are normally made by the embryonic origin trophoblast cells. However, It may be present in most, if not all, types of cancer. These two procedurally totally different methods are being used to ascertain the validity of the often very low amount of the hormone in the blood. The IRMA is immunoradiometric assay, and the IMM is chemiluminescence. The tests will detect extremely low levels of the hormone, and are specific for it 98-99%. The IRMA test will measure down to 0.3 mIU/mL, and IMM to 0.2 mIU/mL. Dr.Schandl named this tumor marker "the pregnancy and/or malignancy hormone." HCG suppresses the immune system, starts and enhances DNA, RNA of protein synthesis, and generally it is produced under anaerobic cellular conditions by the trophoblast.
The HCG Urine test was studied and introduced at American Metabolic Laboratories. This test is now included in our Cancer Profile. It must be noted that American Metabolic Laboratories' Urine-HCG Test may be the one and only one of its kind for being quantitative down to less than 1.1 mIU/mL detection level. This test, unlike Doctor Navarro's for instance, requires about 0.5 mL of urine without any treatment, in its natural form. It is totally specific for the HCG hormone even in minute quantities. The old method requires acetone denaturation and extraction that yields a conglomerate of HCG, LH, FSH, and TSH hormones. All of the four structurally very similar hormones are precipitated by the harsh treatment and will add on to the reported HCG value. Postmenopausal women and older men with high LH and/or FSH, and hypothyroid individuals with high TSH may yield elevated "HCG" values. However, this hormone species is actually HCG-like (HCG-L) with one-half biological activity when compared to pregnancy or tumor generated HCG.
PHI enzyme channels cells into anaerobic metabolism, i.e. fermentation. This kind of cellular survival is what cancer cells favor. The more energy generating metabolic pathway is oxidative phosphorilation. This is the pathway normal cells require in the presence of oxygen. Hence, more oxygen is less cancer, and less oxygen is more cancer. PHI is called the autocrine motility factor, i.e. malignancy or cancer spread factor. This means it is one of the major causes of metastatic spread.
CEA is a broad spectrum cancer marker. It is the carcinoembryonic antigen. It can be elevated in all sorts of cancers. It is very prevalent in cancers of the breast, colon, and rectum. Like all the others, it is an independent cancer marker that by itself may be sufficient as a diagnostic adjunct.
GGTP is the most sensitive test for the liver, however, it may be elevated in diseases of the heart, lungs, and kidneys. It is not a tumor marker however, it may be elevated in cancer patients as a result of either cancer spread or toxic therapy.
TSH or thyroid stimulating hormone regulates basic metabolic rate, i.e. oxygen utilization. A high level, i.e. hypothyroidism, may be a prelude to cancer. Chemotherapy frequently causes this anaerobic condition by injuring the thyroid gland.
DHEA-S is the "adrenal anti stress, pro immunity, longevity hormone", according to Dr. Schandl. The immune system is impaired without adequate amounts of this hormone. Most, if not all cancer patients and those in the process of developing cancer have very low or no DHEA in their blood.
This ultra sensitive method measures low or high thyroid activity
HCG IRMA May be elevated in cancer, stress-related to cancer, a developing cancer, or pregnancy. It will detect only intact hormone. It may not detect HCG-L Normal: Less than 1 mIU/mL; gray zone: up to 3.0 mIU/mL
HCG IMM May be elevated in cancer, stress-related to cancer, a developing cancer, or pregnancy. It measures intact and all other molecular forms of the hormone, including HCGL-S (HCG-like) Normal: Less than 1mIU/mL; gray zone: up to 3.0 mIU/mL
***HCG Urine May be elevated in cancer, stress-related to cancer, a developing cancer, pregnancy, or the presence of HCG like substance (HCGL) Normal: 0.0 - 1.0; gray zone 1.1 - 3.8 mIU/mL
PHI Elevations may warn of a developing cancer; cancer; active AIDS, acute viral disease, acute heart, liver, or muscle disease Normal: Less than 34 U/L; gray zone: up to 40.00 U/L
GGTP Diseases of the liver, pancreas, and the biliary system. Also heart, lung, kidney ailments Normal: Females less than 29 IU/L, Males less than 35 IU/L
TSH Thyroid stimulating hormone, for thyroid and oxygen metabolism. Normal: 0.4 - 4.0 mcIU/mL
DHEA-S Adrenal anti-stress, immunity, and longevity hormone; low or zero in most cancer patients Normal: Females 35 - 430 mcg/dL, Males 80-560 mcg/dL. Results must be interpreted in reference to a person's age
CEA Carcinoembryonic antigen may be elevated in any malignancy Normal: Less than 3.0 ng/mL; gray zone is 3.1 - 5.0 ng/mL
American Cancer Society. Tumor Markers. What Are Tumor Markers? Revised: 01/04/2006.
American Association for Clinical Chemistry. Lab Tests Online. CA 15-3. Last reviewed on June 24, 2006.
American Society of Clinical Oncology. ASCO Patient Guide: Tumor Markers for Breast Cancer. Last Updated: October 22, 2007.