Do breast cancer treatments lower your immune system?

Last updated 24 June 2022.

Some cancer treatments, such as chemotherapy, affect the immune system making it harder for the body to fight infections. This can increase the risk of becoming seriously ill if you get Covid-19, although being fully vaccinated is the best protection against serious illness due to Covid-19. 

However, not all cancer treatments affect the immune system.  

Read more about breast cancer treatment and Covid-19 risk.

Taking hormone therapy, including tamoxifen, letrozole, anastrozole, exemestane and goserelin, does not affect your immune system. 

Hormone therapies do not increase your risk of getting coronavirus or of becoming seriously ill if you do get it. 

Covid-19 vaccines are safe and effective for people having hormone therapy.

Having trastuzumab (Herceptin) could mean you’re more at risk of getting coronavirus or becoming very ill if you get it. 

The risk is likely to be higher if you’re having it with chemotherapy.   

However, being fully vaccinated against Covid-19 reduces the risk.

Having lymph nodes removed does not affect your body’s ability to fight infections.   

It’s common to have lymph nodes under the arm removed as part of surgery for breast cancer.   

While having lymph node surgery increases the risk of a condition called lymphoedema, having nodes removed or having lymphoedema does not affect the overall ability of the immune system to fight infection. 

Find out more about vaccinations after lymph node removal.

Having certain treatments for breast cancer could mean you’re more at risk of getting an infection such as Covid-19, and more at risk of becoming seriously ill if you do get it. 

However, most people having cancer treatment will have been fully vaccinated, reducing the risk of serious illness.

People considered more at risk include those having: 

• Chemotherapy 
• Immunotherapy or targeted (biological) therapies such as trastuzumab emtansine (Kadcyla) or everolimus (Afinitor) 
• Trastuzumab (Herceptin), or trastuzumab with pertuzumab (Perjeta), with or without chemotherapy (the risk is likely to be smaller if you’re not having chemotherapy as well) 
• Other targeted (biological) therapies which can affect the immune system, including palbociclib (Ibrance), ribociclib (Kisqali) and abemaciclib (Verzenios) 

Compared with chemotherapy drugs, targeted therapies tend to have fewer serious side effects. However, they can still cause problems in some people. 

Because of this, it’s best to contact your hospital team to check your individual risk. 

People on these treatments usually have regular blood tests to check their white blood cell count. A low white blood count means you’re more at risk of infection. 

If you’re having any of these treatments, you may be advised to take extra precautions to protect yourself.

The government recommends everyone follow the same actions to reduce the risk of catching Covid-19 or passing it on to others. These are:

• Get vaccinated
• Let fresh air in if you’re meeting others indoors
• Wash your hands, cover coughs and sneezes, and clean your surroundings frequently
• Wear a face covering or mask, especially in crowded, enclosed spaces.

There's no longer separate guidance for people previously classed as being clinically extremely vulnerable.

While the pandemic has been hard for everyone, it may have been particularly difficult if you were dealing with a cancer diagnosis or going through treatment.  

You may find it helpful to talk to someone about how you’re feeling. You can call our Helpline free on 0808 800 6000. 

You may also find it useful to read our tips on managing stress and anxiety.