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| Tumour markers are substances, usually proteins that are produced by the body in response to cancer growth or by the cancer tissue itself. Some tumour markers are specific for one type of cancer, while others are seen in several cancer types. Tumour markers are used in health screening for screening of cancer and for early diagnosis of cancer when it is the most treatable and before it has had a chance to grow and spread. |
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| Common questions that the public often ask regarding tumour markers are as follows: |
1. Is it necessary to check all these tumour markers?
2. How accurate are these tumour markers? What is the percentage of accuracy? If it is not very accurate, why waste our money doing it?
3. If my tumour markers level is raised, does it mean that I am having cancer?
4. Why does my family doctor tells me that tumour markers are useless and not accurate?
5. I am diagnosed to have cancer (e.g breast cancer), Why is it that my tumour marker(CA153) is normal?
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| As a medical practitioner, I was taught in medical school that only few tumour markers are really useful i.e PSA, AFP and CEA, and most of the tumour markers are used for monitoring of disease status rather than screening. I am sure a lot of doctors also share this belief. However, after a few years working with BP Healthcare Group, I now realize that tumour markers are not as useless as most doctors think they are. Let me share with you two case scenarios which happen to my patients and, hopefully with that, you can decide for yourself whether checking tumour markers are really necessary in health screening |
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Case 1:
Mr A is a 48 years old businessman. He came to our centre for health screening at the end of 2006. He is a chronic smoker and the purpose he came to do the test is because he has been suffering from multiple joints pain mainly small joint of his hands for a few months. He sought treatment from many doctors but with no improvement. No cough, no loss of weight or loss of appetite.His blood test came out to be normal except his CEA. His CEA = 20 (Normal <5) . Since he is a smoker and his symptoms are suggestive of non-metastatic extrapulmonary manifestations of lung cancer, he was advised to do a chest x- ray and was diagnosed to have lung cancer. Currently he is under follow-up with an oncologist |
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Case 2:
Mr B is a 50 years old gentleman who has been diagnosed for diabetes for many years. His diabetes is poorly controlled even with insulin injection. He is a health conscious person and does blood test every year. Last year he came to our centre again for general health screening. His reports are normal except his for his poorly controlled blood sugar and raised in level of CA19-9, about 84 (normal 37), a tumour marker for pancreatic cancer. He was asymptomatic then, experienced no loss of weight or loss of appetite. He was referred to a specialist and CT scan was done. The CT scan of pancreas showed a cyst in the tail of the pancreas. No other masses were seen in the abdomen. After the diagnosis, he sought treatment from Chinese traditional healer and kept on testing his CA19-9 every few months. His CA 19-9 kept rising from below 100 to few thousand in a few months. Early this year, he came for the blood test again, his CA19-9 has risen to > 10000, then, he was advised to do an ultrasound again and was found that there was a tumour in the tail of pancreas and, unfortunately for him, the tumour has actually spread to the liver. He is currently under follow-up with an oncologist. However his CA 19-9 still raised each time he came for retest even under chemotherapy, his latest CA19-9 has gone up to 24000. |
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| So, let us go back to the questions again: |
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| 1. Is it necessary to check all these tumour markers? |
| If you ask me this question 3 years ago, I would probably say no. However, now my answer is YES. The two case scenarios are an eye-opener for me and hopefully will be an eye-opener for others who do not believe in tumour markers. |
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| 2. How accurate are these tumour markers? What is the percentage of accuracy? If it is not very accurate, why waste our money doing it? |
| It depends on which tumours markers, some can be 60-70 % accurate, some probably only 30-40%. When we talk about accuracy, we are looking at the statistics, but we are humans, not numbers, not statistics. Although some accuracy of some tumour markers can be only 30-40%, it can actually save lives if we can detect cancer early in those 30-40% of people with cancer. |
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| 3. If my tumour markers level is raised, does it means that I am having cancer? |
| Most of the tumour markers are protein, so the level can be affected by other diseases or factors. Tumour markers are just screening test. If your tumour markers are raised, you will need to do further test to confirm or rule out cancer. |
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| 4. Why my family doctor tells me that tumour markers are useless and not accurate? |
| Doctors are taught not to believe in tumour markers in medical school, just like myself. Doctors always like to claim that they practise evidence-based medicine, based on research and statistics that are available. Again, we are humans, not numbers or statistics. My previous experience taught me otherwise. Well, it is up to you whom you want to believe. |
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| 5. I am diagnosed to have cancer ( e.g breast cancer ), why is it that my tumour marker ( CA153) is normal? |
| Not all cancer will have raised tumour marker. As have been mentioned earlier, majority of tumour markers are protein. These proteins are secreted by normal cells and cancerous cells, too, but some cancerous cells tend to secrete excessive amount of these proteins, hence, the raised in the level of specific tumour markers. But not all cancerous cells will secrete these proteins, so not all cancer will have raised in tumour markers |
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| I hope after reading this article, you will have a better understanding about tumour markers and have decided whether to check or not to check. However, in my opinion, it is better to check since it is inexpensive and besides, there is no harm in doing it. |
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Prepare by:
Dr. Quah Say Chuan
Medical Doctor
BP Diagnostic Centre, Cheras
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