An antigen is a foreign substance recognized and marked by the body’s immune system to be destroyed. The antigens are found on the surface of all cells, but usually an individual’s immune system does not react against its own cells. When a cell becomes cancer, new antigens (unfamiliar to the immune system) appears on the surface of this cell and the immune system may consider these new antigens, called Tumor antigens as foreign and is able to stop or destroy these cells cancer. However, even fully operational, the immune system does not always destroy all the cancer cells.
Tumor antigens have been identified in several types of cancer, including malignant melanoma, bone cancer (osteosarcoma) and some types of gastrointestinal cancers. People with these cancers can develop antibodies against these tumor antigens, but antigens usually do not produce an adequate immune response to cancer control. In addition, antibodies may be incapable of destroying the cancer and sometimes even seems to stimulate their growth.
However, it is possible to take advantage of certain tumor antigens. The antigens released into the blood by some cancers can be detected by blood tests. Sometimes these antigens are called tumor markers. The possible use of these tumor markers as a method of detecting cancer in people who have no symptoms has gained great interest. However, because tests are expensive and not very decisive, systematic use in research is generally undesirable for most cases. On the other hand, are much more valuable in the diagnosis and treatment of cancer. For example, blood tests can help determine if cancer treatment is effective. If the tumor marker disappears from the blood, therapy has probably been effective. If the marker disappears and then reappears, possibly cancer has returned.
Carcinoembryonic antigen (CEA) is a tumor antigen that is found in the blood of people with colon cancer, breast, pancreas, bladder, ovary and cervix. High amounts of this antigen can also be detected in heavy smokers and in those with liver cirrhosis or ulcerative colitis. Therefore, the presence of a large amount of CEA means the existence of cancer. Measurement of carcinoembryonic antigen values in people who have been treated for cancer, help detect a recurrence of it.
Alpha-fetoprotein (AFP), which is normally produced by liver cells in the fetus is in the blood of people with liver cancer (hepatoma) and often in people with certain cancers of the ovary or testis and children or young adults with tumors of the pineal gland.
Beta-human chorionic gonadotropin (b-HCG), a hormone produced during pregnancy, which serves as the basis for the analysis of the same, also occurs in women who have a cancer originating in the placenta and in men with various types of testicular cancer. This hormone is a useful tumor marker in monitoring therapy for these cancers, as it has helped improve the cure rate in more than 95 percent of cases.
The values of prostate-specific antigen (PSA) are elevated in men with noncancerous growths (benign) prostate and significantly in those with prostate cancer. The value above which should be considered significant is still uncertain, but individuals with a high amount of this antigen should be subjected to other tests to find prostate cancer. With the determination of the amount of prostate-specific antigen in the blood after treatment of cancer, can you tell if it has reappeared.
The CA-125 is another antigen. Their values in the blood rises appreciably in women with various diseases of the ovaries, including cancer and ovarian cancer and is difficult to diagnose, some experts advise determine the CA-125 in women over 40 years. However, its lack of sensitivity and specificity indicates that it is not yet a screening test trial.
Other antigens are found in large quantities, as is the case of CA 15-3 that appears on breast cancer, CA 19-5 in pancreatic cancer, the b2-microglobulin in multiple myeloma and lactate dehydrogenase in testicular cancer but none of them can be recommended as a screening test for cancer. However, it is useful to monitor response to cancer treatment and diagnosis.
Tags: destroying the cancer, Treatment of Cancer, Tumor antigens, ca 15-3, cancer, cea tumor marker, lung cancer tumor antigen, lungs tumor antigens, osteosarcoma bone cancer trials, signs of lung cancer, tumor antigens and lung cancer, tumour lung B-HCG