Understanding The 3 Common Types Of Gastro Tumour Markers
In medical terms, tumours refer to body growths that occur as a result of uncontrolled cell divisions due to several reasons, such as aging, environmental exposure, and genetic mutations. Tumours can be characterised into two: Malignant (Cancerous) and Benign (Non-cancerous).
Tumour markers are by-products of either the body’s response to the presence of a tumour or the tumour itself. However, tumour markers can also be elevated in normal patients who do not have a tumour or cancer, in the general population. Tumour markers are analysed by various methods, such as molecular biology, immunochemical, or biochemical. They may indicate to the doctor details about the cancer, such as its aggressiveness and also help gain insight about the effectiveness or response to treatment. The information is also used during the treatment process to track the cancer relapse.
Some gastrointestinal-related tumour markers include the following:
- Thyroid: Thyroglobulin and CEA
- Oesophagus: CSS and CEA
- Pancreas and stomach: CA72-4, CA 19-9, and CEA
- Bile duct and liver: CA 19-9, AFP, and CEA
- Colorectal: M2-PK, CA 19-9, and CEA
Generally speaking, the common gastrointestinal-related tumour markers (pancreatic, biliary tract, liver, and gastrointestinal cancer) include CA 19-9, carcinoembryonic antigen (CEA), and alpha-fetoprotein (AFP).
1. CA 19-9 (Carbohydrate Antigen 19-9)
CA-19-9 is a glycolipid mostly associated with fetuses and is produced in the epithelium or lining of the pancreas, intestine, and stomach. It exists in significantly lower concentrations in adults. The bile normally eliminates CA 19-9. As a result, a build-up in concentration level might be a sign of bile duct obstruction. In certain cases, a raised level of CA 19-9 could also be part of IBS symptoms and cystic fibrosis.
In terms of detecting cancer, CA 19-9 is the tumour marker of choice for pancreas cancer symptoms. Significant concentration levels of more than 1000U/ml are typically indicative of the presence of lymph nodes. A concentration level of more than 10,000U/ml indicates that the cancer has spread from the pancreas to the surrounding regions.
While CA 19-9 can also be used to screen for stomach cancer, it is typically not the preferred choice as it is not as specific and sensitive.
2. CEA (Carcinoembryonic Antigen)
CEA is a glycoprotein that is produced by fetal tissues as well as tumours. It usually exists in lower concentrations in adult tissues, such as the liver, pancreas, and intestine. Generally, a mild to moderate rise in CEA concentration is commonly associated with benign conditions in the lungs, liver, pancreas, and colon. Such conditions include autoimmune diseases, pneumonia, bronchitis, IBD, pancreatitis, hepatitis, and liver cirrhosis. However, when the CEA concentration spikes exponentially and continually, it may be a sign of malignant colon cancer and metastatic cancers to the lymph nodes, lungs, liver, and bone.
CEA, however, is neither specific nor sensitive as a general screening for colon cancer. It is, instead, used in clinical practice to track the body’s response to colon cancer treatment as well as monitoring of cancer remission and relapse. Hence, we highly recommend individuals conduct gastroenterology visits every five to ten years if they are above 50 years of age or conduct an annual faecal blood screening test.
3. AFP (Alpha-Fetoprotein)
AFP is another glycoprotein that is formed in foetuses. It develops in the fetal embryo’s yolk sac, as well as in the fetus’s gastrointestinal tract and liver. AFP is usually detected in the 4th week of pregnancy. After which, the concentration stabilises around the 12th to 15th week before decreasing until the baby is born. The concentration of AFP continues to decrease until the baby hits one year old and stabilises until adulthood.
An elevated concentration level of AFP raises concern for the development of benign liver conditions, such as hepatitis. It can also be a sign of primary liver cancer, also known as germ cell tumours and hepatocellular carcinoma. A raised AFP concentration may also be present in patients with metastatic colorectal, lung, and breast cancers that have spread to the liver.
AFP, together with another clinical test, is usually used to monitor the therapy process for hepatocellular carcinoma as well as diagnose hepatocellular carcinoma in high-risk individuals, such as those suffering from chronic Hepatitis B infection.
The effectiveness and practicality of tumour markers in general screenings are still debatable. Because there are many various markers for varying cancers, no tumour marker is particularly and sufficiently specific and sensitive. A raised gastrointestinal tumour marker does not formally mean the presence of gastrointestinal cancer. Further tests would still have to be conducted to confirm the presence of cancerous cells.
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