Cancer itself can increase infection risk

Cancer cells can get into the bone marrow where blood cells are made. (See How does your body normally resist infections? for more on bone marrow and blood cells.) The cancer cells then compete with the normal bone marrow cells for space and nutrients. If too many normal bone marrow cells are destroyed or pushed out of the bone marrow, the few cells that are left won’t be able to make enough white blood cells (WBCs) to fight infection.

Cancer can also damage other parts of the immune system. A tumor can grow through the skin or mucous membranes, breaking natural barriers and allowing germs to get in. Tumors may also reduce blood flow to the normal tissues by pressing on them or their blood supply. Tumors in the lungs may block normal mucus drainage, which can lead to infections. And tissues that have been damaged by cancer are more prone to infections.

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