What makes people with cancer more likely to get infections?

Some types of cancer can damage the immune and blood systems or change the way they work. For instance, lymphoma (Hodgkin and non-Hodgkin) and most types of leukemia start in immune system cells. They change the immune system cells so that cells that once protected your body begin to interfere with the normal way your immune system works. Many other types of cancer can also affect the immune system.

In most cases it’s not the cancer itself but the cancer treatment that changes the immune system. Treatments can cause short- or long-term damage. For example, long-term damage happens when immune system organs such as the spleen are removed. A splenectomy (surgery to remove the spleen) is sometimes done to remove cancer or learn how much it has spread. On the other hand, radiation therapy, immunotherapy, and chemotherapy, either alone or in combination can lead to short-term immune system damage. A bone marrow or stem cell transplant uses very strong treatments to kill cancer cells. This treatment also kills immune system cells, which can worsen and prolong the risk of infection. Sometimes this damage can last for months after treatment ends.

Some people with cancer have a higher risk of infection because of the changes in their body’s defense systems. Cancer and cancer treatments can affect these systems in different ways. People with cancer might be more likely to get infections because of:

All of these can increase your risk of infection by causing low white blood cell counts and a weak immune system (discussed in a later section).

The American Cancer Society medical and editorial content team

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.

Last Medical Review: February 16, 2015 Last Revised: February 25, 2015