A lowered level of immunity is called immunosuppression. Certain diseases, including cancer, and certain treatments, including chemotherapy and radiation therapy, can cause some people to have immunosuppression. This is usually referred to as having a low white blood cell count, but you might hear other words to describe it too.
Neutropenia is defined as a lower than normal number of neutrophils (a type of white blood cells). White blood cells are part of the immune system. There are different types of white blood cells, and they each have a key role in the body’s defense against germs:
Neutrophils form a very important defense against most types of infection. Normally, most of our white blood cells are neutrophils. In patients with cancer, neutropenia is usually caused by treatment. When looking at your risk of getting an infection, doctors look at the number of neutrophils you have.
If your neutrophil count is low, the doctor may say you are neutropenic. For most people with cancer, having a low neutrophil count is the biggest risk factor for getting a serious infection. Ask your doctor if your cancer treatment will cause your neutrophil count to drop.
Some treatments, most often those given during a bone marrow (stem cell) transplant, can cause a shortage of lymphocytes. B and T lymphocytes help fight viruses, but have different jobs:
You might hear your doctor or nurse talk about your absolute neutrophil count or ANC. This is the number of neutrophils you have in a certain amount of blood. Your health care team will use your ANC to get an idea of how well your immune system might work during treatment. A blood test called a complete blood count (CBC) is used to see how well your immune system is working. It measures your white blood cells (WBCs), and your cancer care team is able to figure out your ANC from your WBC count. Your cancer care team will use your ANC to get an idea of how your immune system is affected by treatment and how well it is working to protect you from infection.
As the ANC gets lower, the usual signs of infection, such as fever, pus, pain, swelling, and redness, may not show up when an infection starts. This is because these signs are caused by neutrophils fighting off germs, and if you don’t have enough neutrophils to fight infection, you won't produce the signs. This can make it hard to know if you have an infection. The good thing is that another WBC, called the monocyte, can still cause signs of infection in a person who has neutropenia. Sometimes in people with severe neutropenia a fever may be the only sign of an infection. The lower your ANC is and the longer it stays low, the higher your risk of infection will be.
Ask your doctor if your cancer treatment might cause your neutrophil count to drop. Your cancer care team will help you find the ANC on your lab results and can help explain more about it.
Treatment may include one or a combination of the following:
Talk to your cancer care team about what to watch for. Call your doctor if you have a fever (your cancer care team will let you know what temperature they consider a fever) or any other symptoms of neutropenia.
Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.
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Last Revised: November 17, 2022