What are oncomarkers?
Why do they prescribe an analysis and how accurate are its results?
Recently, an increasing number of people are turning to laboratories in order to pass tests for cancer markers. Why do we need such tests? How complete information do they give? And what exactly are cancer markers? Let's try to understand these issues.
Cancer markers are substances of various nature: hormones, proteins, enzymes, the number of which can increase with tumors. These substances are secreted either by the tumor itself, or by cells located next to the neoplasm. Cancer markers can also appear in the blood as a reaction of the body to the presence of a tumor.
Currently, experts know about 20 cancer markers, among which the most common are:
- PSA (prostate specific antigen). It is produced in the prostate and is a "harbinger" of prostate cancer;HCG (human chorionic gonadotropin).
- It is used to diagnose tumors of chorionepithelioma, vesicular drift in women and testicular tumors in men;CA-125 may indicate the development of ovarian cancer in women, but it may also be a signal of a benign tumor.
- REA (cancer-embryonic antigen).
- It is produced by the cells of the digestive tract of the embryo and fetus and, according to the results of the analysis, can cause such diagnoses as stomach cancer, liver cancer, colon and rectal cancer, lung cancer;AFP (alpha-fetoprtein).
- In adults, an increase in AFP is most often a consequence of chronic hepatitis, hepatocellular carcinoma or germinal cell tumors.MCA (mucin-like cancer-associated antigen).
- A glycoprotein contained in breast cells. Its level increases in the blood in breast cancer or tumor metastases in other organs and tissues.When and why do they prescribe an analysis for cancer markers?
First of all, a blood test for cancer markers is prescribed to people who have a predisposition to the appearance of a tumor.
In recent years, there has been an increase in cancer, including among young people. Many of them have become more serious about their own health. These people first undergo genetic testing, which allows them to determine the risk of certain diseases, including cancer. If there is one, then the first step in the warning is an analysis for cancer markers.
And of course, such studies are necessary for those who have already detected tumors. In this case, these tests are a kind of control points: whether the method is chosen correctly, how fast the recovery process is going. Even if the treatment was successful and the disease receded, doctors recommend periodically donating blood for cancer markers.
It is worth noting that oncology, as a science, is constantly developing – new drugs are being created, unique techniques are being developed. All this makes it possible to effectively fight cancer in the early stages, and it is possible to diagnose the disease at the very beginning just with the help of tests for cancer markers.
How accurate is the information provided by tests for cancer markers?First, it should be noted: cancer markers in clinical oncology are taken for dynamic monitoring.
If the initial level of cancer markers is unknown, it makes no sense to take tests in the future, since it very often happens that the level of the cancer marker rises when the disease is at a critical stage.
Secondly, there is no "universal" cancer marker that could directly indicate a specific localization of cancer. Most antigens have a sensitivity of 70-80 and only some have a sensitivity of 90 percent. Therefore, markers are not used as an independent method of diagnosing a malignant tumor. But in combination with other diagnostic techniques and tests, they can serve as a more accurate diagnostic tool.
And thirdly, cancer markers can deceive. For example, the CA antigen is considered by many to be an early marker of breast cancer. This is absolutely wrong. Therefore, today a group of tumor markers of CA (there are several varieties) is used as an indicator by which oncologists evaluate the radicality of each stage of the special treatment of breast cancer and ovarian cancer.
Cancer markers can be normal even in the presence of cancer. In addition, cancer markers can be false positive during pregnancy, increase in acute inflammatory or chronic diseases (hepatitis, cirrhosis of the liver, endometriosis, heart failure, etc.).
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30.09.2015