Blood tests for secondary breast cancer

You might have blood tests for secondary breast cancer to look at a range of things. For example, to look at:

  • how well your kidneys and liver are working
  • the numbers of different blood cells
  • the level of calcium in your body

Before your blood test

You can eat and drink normally before most blood tests. Your doctor will tell you if you need to stop eating and drinking beforehand and for how long. This is called fasting. Tests that you might need to fast for include:

  • glucose tests
  • cholesterol tests

For tests that check the levels of particular substances in the blood you might need to stop taking certain tablets, such as iron or thyroxine. Check with your doctor beforehand to see if you need to stop taking tablets.

What happens?

You sit or lie down to have the test.

A doctor, nurse or phlebotomist (person specialised in taking blood) chooses the best vein to use. This is usually from your arm or hand. Let them know if you are afraid of needles, get unwell with the sight of blood or are allergic to plasters or latex. 

They put a tight band (tourniquet) around your arm above the area where they take the sample. You may need to clench your fist to make it easier to find a vein.

They clean your skin and then put a small needle into your vein. Next, they attach a small bottle or syringe to the needle to draw out some blood. They might fill several small bottles.

Once they have all the samples, they release the band around your arm. They then take the needle out and put pressure on the area with a cotton wool ball or small piece of gauze for a few minutes. This helps to stop bleeding and bruising.

Look away when they’re taking the blood if you prefer. Tell your doctor, nurse or phlebotomist if you feel unwell.

Photograph of a blood test

Getting your results

Ask the phlebotomist, doctor or nurse when and how you will get your results. Some results might be available quickly, such as a full blood count. But some other tests might take several weeks.

Possible risks

Blood sampling (phlebotomy) is a safe test. There is a possibility of:

  • bleeding and bruising - pressing hard when the needle is removed can help to stop it
  • pain - this is normally mild and can last for a few minutes
  • swelling (oedema) - ask your nurse, doctor or phlebotomist to avoid an arm that is swollen or has a risk of swelling
  • feeling faint or fainting - tell the person doing your blood test if you're feeling lightheaded or dizzy at any time
  • infection - this is very rare

Types of blood tests

Tumour marker blood test  

Tumour markers are substances that might be raised if there is a cancer. They’re usually proteins that can be found in the blood.  

A tumour marker that is sometimes used in breast cancer is a protein called CA 15-3.

Doctors may use the CA 15-3, along with other tests, to check if treatment is working. A raised level may suggest that the cancer is spreading in some people with secondary breast cancer. 

Tumour marker tests are not reliable enough to use on their own to:

•    diagnose breast cancer 
•    make decisions about your treatment

This is because other non cancerous conditions can also cause the levels to rise.

Full blood count

A full blood count (FBC) measures the number of red cells, white cells and platelets in your blood.

  • Red cells carry oxygen around our bodies. Haemoglobin is the part of the cell that carries oxygen. If you have a low red cell count, your doctor might say you’re anaemic (pronounced a-nee-mic). This can make you feel tired, short of breath and dizzy.
  • White cells fight infections. There are several different types of white cells, including neutrophils and lymphocytes.
  • Platelets help clot the blood, for example after a cut. Symptoms of a low platelet count include abnormal bleeding, such as bleeding gums and nosebleeds.

There is a range of normal for blood counts. The range of figures quoted as normal varies slightly between laboratories and also differs between men and women. 

Diagram of table showing the normal values of men and women

Urea and electrolytes

These blood tests show how well your kidneys are working. Waste chemicals called urea and creatinine are produced by the body. Our kidneys remove them from our blood and get rid of them in our urine.

Electrolytes are substances such as sodium, potassium, chloride and bicarbonate.

Calcium level in the blood test

Depending on your situation, your doctor might check the levels of calcium in your blood.

Damaged areas of bone can release calcium into your bloodstream. This can happen if you have breast cancer that has spread to the bones. You can have treatment to lower the levels of calcium.

Liver function tests (LFTs)

Liver function tests (LFTs) check how well your liver is working. LFTs look for levels of enzymes and proteins made by the liver or which are cleared by the liver. They include:

  • alanine aminotransferase (ALT)
  • aspartate aminotransferase (AST)
  • alkaline phosphatase (ALP)
  • gamma-glutamyl transferase (Gamma GT)

They might be raised if you have a blockage in your liver or bile duct, or if you drink a lot of alcohol.

LFTs also look at the amount of bilirubin in the blood. This is a chemical in bile Open a glossary item. Bilirubin can be raised if you have a problem with your liver or gallbladder. Bilirubin can cause yellowing of your skin and eyes (jaundice). 

LFTs also measure albumin. This is a protein in the blood that can be low when you have some types of cancer. You can also have low albumin if you’ve been eating small amounts and are malnourished.

Treatment

Depending on your symptoms and blood test results, you may have treatment. This might be treatment to relieve your symptoms and, or slow the growth of your breast cancer.

Last reviewed: 
04 Mar 2021
Next review due: 
04 Mar 2024
  • Oxford handbook of clinical medicine (10th edition)
    M Longmore and others
    Oxford University Press, 2017

  • The Royal Marsden Manual of Clinical Nursing Procedures (10th edition)
    S Lister, J Hofland and H Grafton 
    Wiley Blackwell, 2020

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