Blood Test for Cancer Detection
Blood test for cancer are not recommended as exclusive diagnostic tools for cancer detection. Other diagnostic methods are utilized in combination to detect the presence of the disease. Although, blood tests do not provide conclusive information about detection of cancer. They are use to identify cancer markers, also called tumor markers or biomarkers, in the blood, which provide useful clues for screening high-risk individuals for specific types of cancer.
The advantage here is that tumor markers, in most instances, appear in the blood before an individual begin to exhibit symptoms. Furthermore, tumor markers can be use to improve strategies for treatment of an already develop cancer. For example, doctors may use a tumor marker test result to decide whether to include therapies such as immunotherapy or chemotherapy to a pre-existing treatment in order to enhance therapy efficacy.
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Can a blood test detect cancer?
Blood tests can be used to help in the cancer diagnosis process but they cannot be use on their own to make a decision that cancer is present. Blood tests are important in the sense that when they reveal positive results for cancer, tissue biopsies can then obtain for further tests to confirm the suspected diagnosis. An overview of cancer blood tests are as follows:
Complete blood count (CBC)
In general, this lab test measure the level of red blood cells (RBCs), white blood cells (WBCs) and platelets (non-nucleus, disk-shape cell fragment present in blood which are important for blood clotting) in a blood sample. In certain cancers, such as multiple myeloma (cancer of the plasma cells in the bone marrow) and myeloid leukemia (blood and bone marrow cancer in which there are elevated immature white blood cells), the ratios of RBCs: WBCs: Platelets are altered markedly, because cancer had outgrowth the other cell types in the bone marrow. For instance, low RBC or platelet counts are commonly found, with abnormally high levels of WBCs. Accordingly, analysis of bone marrow biopsy confirms this result.
Blood protein tests for cancer
A blood serum protein electrophoresis (SPEP):
This assay is performed to detect abnormalities of the immune system proteins called immunoglobulins (Igs) that are sometimes elevate in people with multiple myeloma. One of the cell types of the bone marrow has excess production of a type of immunoglobulin called a monoclonal protein, M-protein or myeloma protein, which can be identified using this assay. Other tests, such as analysis of bone marrow biopsy, are used to confirm a suspect diagnosis.
Enzyme-linked immune sorbent assay (ELISA):
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This assay is performed to detect beta-2 protein in multiple myeloma blood or in the blood of a patient suspicious of kidney cancer. In both of these cases, the levels are highly elevate.
Free light chain assay:
This assay is performed to measure elevated levels of free light chains in multiple myeloma cancer. The immune system proteins called immunoglobulins (Igs) consist of smaller units called heavy chains and light chains which are assembled to form a whole large Ig complex. In multiple myeloma, most of the M-proteins are not the whole antibody. This assay is very sensitive so it can detect increased levels of free light chains. It is, therefore, very useful for early detection of multiple myeloma. Additionally, the assay can be used to monitor responsive treatment, in which case, the levels will fall over a time.
Blood chemical tests for cancer
The levels of some chemical become elevated in certain types of cancers such as high bilirubin (broken down red blood cells) as a result of liver damage in liver cancer, excess urea or uric acid and creatinine (waste product generated from muscle metabolism) in the blood stream in kidneys cancer because of loss of kidney function, elevated calcium levels, as a result of complications from multiple myeloma or myeloid leukemia and high blood glucose in pancreatic cancer. Therefore, their levels in the blood can be measure as an indication for specific cancers.
Blood Cancer tests for tumor markers
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On the whole, tumor marker are abnormally high tumor express gene product (proteins made in excess of tumor cells) that can be detect in your blood. Tumor markers are also produce by normal cells in your body but the levels are much lower than what is observe in cancer, so the test compare normal levels with the abnormally high levels express and release into the blood in the disease state. It is important to be aware that other disease conditions can also bring about the elevation of some of these tumor marker, this limits the potential for diagnosis of cancer, using just one method. Thus there is always the need for other testing procedure to be use as confirmation.
Prostate Specific Antigen (PSA) Test:
In short, this test is commonly used as a screening tool for the early detection of prostate cancer, PSA testing measures levels of a protein produced by prostate gland cells, called prostate-specific antigen, in the blood. To clarify, elevated levels of PSA can give your doctor an early indication of the development of prostate cancer. However, it is important to note that a number of benign prostate conditions can also cause PSA levels to rise.
Carcinoembryonic Antigen (CEA) Test:
This antigen, while present in a developing fetus, is not normally present in the blood of healthy adults. When detected in the blood by CEA testing, it can indicate the presence of one of several forms of cancer, including cancers of the colon, rectum, pancreas, breast, ovary or lung.Cancer Antigens for Breast, Pancreatic and Ovarian Cancer
AFP (Alpha-Fetoprotein) Test:
This is a protein produce by the liver and yolk sac during pregnancy. Measurement of elevated AFP in the blood serves as a tumor marker for liver, certain types of ovarian cancer and embryonic testicular cancer (when the developing testis of the fetus is cancerous during pregnancy).While this antigen is found in the blood of healthy pregnant women, since it is produced by fetal development, it is not normally present in adult men or non-pregnant women.
Cancer Antigen 125 (CA-125) Test:
This antigen is used as a tumor marker for ovarian cancer. A protein found on the surface of many ovarian cancer cells, blood tests to measure levels of this antigen are used to aid in diagnosing ovarian cancer, further monitoring the progress of ovarian cancer treatments and detecting a recurrence of the disease.
Cancer Antigen 19-9 (CA 19-9) Test:
This blood test looks for antigens in the bloodstream that are used as markers for pancreatic cancer. It can be used to help diagnose cancer of the pancreas as well as to monitor treatment progress.
Cancer Antigen 27.29 (CA 27.29) Test:
The CA 27.29 blood test measures the level of CA 27.29 antigen in the bloodstream, which is an indication of breast cancer. This test is the only blood test that is specific to cancer of the breast, and is used to aid diagnosis, monitor treatment and detect the spread of breast cancer to other parts of the body.
Human Chorionic Gonadotropin (hCG) Test:
A well-known indicator of early pregnancy, hCG is also produced by some cancer cells and is considered a tumor marker, helping to detect germ cell cancers in men and non-pregnant women. In fact, Germ cell cancers are tumors that develop from an egg or sperm, including testicular and ovarian cancers.
Examples of tumor marker proteins whose levels can be measure using this technique include, prostate-specific antigen (PSA) elevation in prostate cancer, cancer antigen 125 (CA 125) elevation in ovarian cancer, CA 19-9, a rare antigen whose levels are elevate in pancreatic cancer, CEA (Carcinogenic Embryonic Antigen) presence in blood might also indicate pancreatic cancer, calcitonin elevation in medullary thyroid cancer, alpha-fetoprotein (AFP) for liver cancer.
An elevated level of human chorionic gonadotropin (HCG) hormone is an indication of germ cell tumors, such as ovarian and testicular cancers. CA15-3 is elevate in breast cancer. Tumor markers are either produce by the tumors themselves or by the body in response to the development of cancer.
In a number of case, the tumor marker level are monitor by follow-up testing over a period of time to assess treatment response. Doctors uses the follow-up testing results to tell if the therapy is working or if the cancer is rather growing.
Alkaline Phosphatase (ALP) Assay:
To summarize, this is an enzyme (one of the proteins that help chemical reactions to go on faster in cells of the body) found in all cells of the body. However, its level in the blood is elevated in liver disease or liver cancer and in several bone diseases, including bone cancer.
Blood Protein Test :
This blood test that looks for certain abnormal immune system proteins (immunoglobulins) in the bloodstream to detect multiple myeloma, a cancer of the blood.
Radioimmunoassay (RIA) for measuring various cancer antigens:
All in all, this is a very sensitive antigen antibody binding assay which utilize radiolabel version of protein being measure in blood serum . By adding serum sample, the cold antigen displays the label antigen from the antigen-antibody complex.
Blood cancer tests for detecting circulating tumor cells:
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Certain blood tests have been develop to determine cells that have broken away from an original cancer site and are floating in circulation (blood flow). In general, the aim of this approach is to enable diagnosis of cancer in advance stage. To sum up, the CellSearch Circulating Tumor Cell (CTC) test is a simple blood test involving immunomagnetic sorting of the circulating tumor cells, fluorescent labeling and detection using CellSpotter Analyzer which is a semiautomate fluorescence microscope that select, align and enumerate the fluorescently label cell, capture as image and automatically present in a classified gallery format. CTC tests help Cancer Doctor (Oncologists) in the diagnosis of metastatic cancers. The CellSearch test is the only FDA-approve test for CTC assessment.
In fact, blood tests that can detect the signs of various forms of cancer are important diagnostic tools, often providing the first indication that a person may have cancer. Further testing is necessary for a definitive diagnosis. Generally, that will include biopsy, which is a procedure to obtain a sample of potential cancerous cells for testing.
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