Written By: Dr Anitha Anchan | Updated : April 29, 2016 3:10 PM IST
Cancer is an abnormal, uncontrolled division of cells. It is a group of over one hundred diseases and can originate in almost any tissue of the body. According to WHO, various kinds of cancers cause about 5 lakh deaths in India annually, and 4 in 10 of them can be prevented just with lifestyle changes like giving up smoking, cutting down on alcohol, eating a healthy balanced diet, etc. Most cancers are diagnosed in advanced stages leading to very poor outcomes and very high death rate. Early detection followed by appropriate treatment can help increase survival rate and improve the quality of life. There are ten life-saving tests for a better health
Cancer screening blood test what is it?
Specific proteins and circulating tumor cells are produced by the cancerous tissues. A cancer screening blood test detects cancer activity in your body by measuring these cancer markers with simple blood tests. There are various tests like fecal occult blood testing (FOBT), CA125 test, PSA test, alpha-fetoprotein blood test, etc. which screen different types of cancers. Screening for cancer is recommended once a year.
Onko-sure is a minimally invasive single blood test that screens 13 different types of cancers including lung, colon, rectum, ovary, liver, etc. at the earliest stage of the disease. The test detects the presence of protein marker called fibrinogen degradation products (FDPs). FDPs are produced when cancer breaks down its surroundings to facilitate tumor growth.
PSA test measures the blood levels of prostate specific antigen (PSA). The antigen is a tumor marker produced in elevated quantities by the prostate gland in prostate cancer.
CA 125 test measures the blood levels of cancer antigen-125. The tumor marker is raised in the case of ovarian cancer, and the test helps in early detection of the cancer.
Alpha-fetoprotein blood test can help early detection of liver cancer in high-risk people.
Carcinoembryonic antigen (CEA), usually present at very low levels in the blood, may be raised in some types of cancer like colorectal cancer, lung cancer, medullary thyroid cancer, etc. A new blood test has been developed that could help detect colorectal cancer in its early stages.
CA 15-3 and CEA are the most widely used serum-based tumor markers for breast cancer. CA 15-3 is used for predicting outcome in newly diagnosed breast cancer patients and also in monitoring therapy in patients with advanced breast cancer [1].
Beta-HCG can be used as a tumor marker in testis and germ cell tumors as well as to monitor osteosarcoma treatment [2].
When is the test recommended?
Cancer screening tests are a proactive approach towards cancer diagnosis. They are recommended to check for cancer before you have symptoms. Screening people regularly for cancers of the breast, cervix, colon, etc. is recommended. Some cancer screening tests are recommended for individuals who are at a high risk. The tests help catch cancer at an early stage where treatments have the greatest likelihood of curing the disease. These tests may also be suggested during and after the treatment of certain cancer to monitor them. Screening for PSA is advised at the age of 50; earlier, if a family member had prostate cancer.
Reading your cancer screening test
Higher than normal levels of the markers may be found in the blood if you have cancer. Some of the normal values are:
CA 125: <35 U/mL
PSA: < 4.0 ng/mL
CEA: < 2.5 g/L
But these tests are not diagnostic. Factors such as age, race, medications, some medical conditions and procedures, etc. can affect the levels. The test may be false positive or negative. Some healthy cells in the body also produce the tumor markers. Hence, you may have elevated levels even in the absence of cancer. Similarly, the blood levels of the markers may be normal even if you have cancer. Hence, these tests can be used in conjunction with other investigations like imaging and biopsy to confirm the diagnosis.
References:
1. Duffy MJ. Serum tumor markers in breast cancer: are they of clinical value? Clin Chem. 2006 Mar;52(3):345-51. Epub 2006 Jan 12. Review. PubMed PMID: 16410341.
2. Boss DS, Glen H, Beijnen JH, de Jong D, Wanders J, Evans TR, Schellens JH. Serum beta-HCG and CA-125 as tumor markers in a patient with osteosarcoma: case report. Tumori. 2011 Jan-Feb;97(1):109-14. PubMed PMID: 21528673.
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