What are lung cancer tumor marker tests?
Lung cancer tumour markers are substances produced by tumour cells. Normal cells can turn into tumour cells due to a genetic mutation, a change in the normal function of genes. Genes are the basic units of heredity passed down from your mother and father.
Some genetic mutations can be inherited from your parents. Others are acquired later in life due to environmental or lifestyle factors. The mutations that cause lung cancer are usually due to acquired, also known as somatic, mutations. These mutations are most often, though not always caused by a history of tobacco smoking. A genetic mutation can cause a lung tumour to spread and grow into cancer.
There are different types of mutations that cause lung cancer. A lung cancer tumor marker test looks for the specific mutation that may be causing your cancer. The most commonly tested lung cancer markers include mutations in the following genes:
- EGFR, which makes a protein involved in cell division
- KRAS, which helps control the growth of tumors
- ALK, which is involved in cell growth
Not all lung cancers are caused by genetic mutations. But if your cancer is caused by a mutation, you may be able to take a medicine that’s designed to attack your specific type of mutated cancer cells. This is called targeted therapy.
Other names: Lung cancer targeted gene panel
What are they used for?
Tests for lung cancer tumor markers are most often used to find out which, if any, genetic mutation is causing your lung cancer. Lung cancer markers may be tested individually or grouped together in one test.
Why do I need a lung cancer tumor marker test?
You may need a lung cancer tumor marker test if you have been diagnosed with a type of lung cancer called non-small cell lung cancer. This type of cancer is more likely to have a genetic mutation that will respond to targeted therapy.
Targeted therapy is often more effective and causes fewer side effects than chemotherapy or radiation. But it’s important to know which mutation you have. Targeted therapy medicines that are effective in someone with one type of mutation, might not work or maybe dangerous to someone with a different mutation or no mutation.
What happens during a lung cancer tumor marker test?
A health care provider will need to take a small sample of the tumor in a procedure called a biopsy. It may be one of two types of biopsies:
- Fine needle aspiration biopsy, which uses a very thin needle to remove a sample of cells or fluid
- Core needle biopsy, which uses a larger needle to remove a sample
Fine needle aspiration and core needle biopsies usually include the following steps:
- You will lay on your side or sit on an exam table.
- An x-ray or other imaging device may be used to locate the desired biopsy site. The skin will be marked.
- A health care provider will clean the biopsy site and inject it with an anaesthetic so you won’t feel any pain during the procedure.
- Once the area is numb, the provider will make a small incision (cut) and insert either a fine aspiration needle or core biopsy needle into the lung. Then he or she will remove a sample of tissue from the biopsy site.
- You may feel a little pressure when the needle enters the lung.
- Pressure will be applied to the biopsy site until the bleeding stops.
- Your provider will apply a sterile bandage at the biopsy site.
Will I need to do anything to prepare for the test?
You may need to fast (not eat or drink) for several hours before the procedure. Talk to your health care provider if you have any questions about preparing for your test.
Are there any risks to the test?
You may have a little bruising or bleeding at the biopsy site. You may also have a little discomfort at the site for a day or two.
What do the results mean?
If your results show you have one of the lung cancer markers that may respond well to targeted therapy, your provider may start you on treatment right away. If your results show you do not have one of these lung cancer markers, you and your provider may discuss other treatment options.
Genetic testing takes longer than many other types of lab tests. You may not get your results for a few weeks.
If you have questions about your results, talk to your health care provider.
Is there anything else I need to know about lung cancer tumor marker tests?
If you have lung cancer, it’s important to see your health care provider regularly throughout your treatment and afterward. Lung cancer can be difficult to treat, even if you are on targeted therapy. Close monitoring with frequent checkups, and periodic x-rays and scans is recommended for the first five years after treatment, and yearly for the rest of your life.
References
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