Tumor Marker Blood Tests

The following article describes that it is common for Malaysians to request tumor marker blood tests as part of their yearly medical checkup.  These blood tests are rarely done by physicians in the US as part of a preventative regimen and mainly utilized to guide treatments or if there are already signs of cancer or a family history of the disease.   Tumor marker blood tests screen for certain products that specific types of cancer produce and release into the blood.  The Carcinoembryonic antigen (CEA), Alpha feto-protein (AFP), CA 19.9, and Prostate specific antigen (PSA) blood tests are described.  The article accurately states that the tests are not 100% sensitive and potentially positive results should be interpreted by a doctor. 

Marked for Cancer

To detect the presence of cancer, tests can be carried out to track for tumour markers

Sun2Surf by Earn Gan

Most Malaysians who go for yearly medical checkups request for tests to detect tumour markers. A string of blood tests are carried out to detect different types of cancer. These tests basically check for tumour markers – substances that can be found in the body when cancer is present.

Cancer/tumour markers can be found in the blood or urine. They are the products of cancer itself or a product of our body in response to certain cancer or condition.

Some of these are marker specific for one particular cancer; some are markers for many types of cancer. There are many types of markers and they are generally used to diagnose cancer, to determine the prognosis and to detect recurrent cancer.

Common cancer marker

» Carcinoembryonic antigen (CEA)

This marker is sometimes detected in patients with colon cancer. However, for healthy people, CEA should not be used to screen for colon cancer, as this test cannot tell for sure whether or not someone has colon cancer.

This marker can be appear normal in person with colon cancer and can be high in conditions other than cancer. The main usage of CEA is to monitor the response of patients with confirmed colon cancer towards treatment and to detect early recurrence of cancer after surgery or treatment. This marker can be high in some non-cancerous conditions such as colitis (inflammation of colon), non-cancerous tumour of intestine, certain liver disease, and chronic lung disease. Smoking can also increase CEA level.

» Alpha feto-protein (AFP)

This marker is present in most liver cancer patients but again, not all. In patients with liver tumour, high AFP above a certain level means liver cancer. A high level of AFP is also present in people with inflammation of liver, certain testicular tumour or a rarer form of ovarian tumour.

» CA 19.9

This is a marker for cancer of the gastrointestinal tract, particularly cancer of the pancreas. In the early stage of pancreatic cancer, the level can be normal. It can be high in patients with colon cancer, stomach cancer, liver cancer and bile duct cancer. It can also be elevated in certain non-cancerous conditions such as thyroid disease, pancreatitis (inflammation of pancreas), colitis and certain female reproductive organ diseases such as endometriosis.

» Prostate specific antigen (PSA)

It is one of the more sensitive tumour markers. It is a protein produced by prostate and is elevated in patients with prostate cancer. However, it can also be elevated in men with benign prostate hypertrophy and infection or inflammation of the prostate. It is higher in the elderly and temporarily elevated after ejaculation. Many doctors do not recommend using it as a general screening test even though it is quite sensitive. It is mainly used to monitor the progress or prognosis of prostate cancer after treatment.

» Limitations

Most of these markers are not 100% sensitive. The reading can be normal even if a person has that particular tumour. Please be aware that this kind of phenomenon is not only seen in early cancer, it also happens in very advanced cancer.

These markers are not specific. The level can be high but not related to any cancerous tumours at all.

Some markers are not specific for one type of cancer. Further tests and investigations are needed to figure out what type of cancer a person is having.

Please do not have a false sense of security when the reading is normal. Some people think normal cancer marker levels mean no cancer, which is not true. As mentioned above, the markers are not sensitive in screening for cancer among the population.

If you want to screen for cancer, you should go to your doctor and have a proper examination and investigations done for that particular organ system. For example: mammogram for breast cancer; ultrasound for liver, pancreas, reproductive organ and prostate cancer; endoscopy for stomach and colon cancer.

If you have a mildly elevated marker and all the investigations are normal, you should consult your doctor for further evaluation. If you have a very high marker level, do not panic. Go to your doctor and get all investigations done as soon as possible.

Do not rely on cancer marker screening to prevent cancer. If you have strong family history of cancers, or symptoms that worry you, seek appropriate medical advice from your doctors.

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