What causes anemia during cancer treatment?

Cancer treatments such as chemotherapy and radiation therapy can cause anemia. Cancers that affect the bone marrow—the soft tissue inside bones where blood cells are made—can cause it as well.

Anemia is a condition in which the number of red blood cells is below normal. Red blood cells carry oxygen from your lungs throughout your body to help it work properly. When you are anemic, your body does not have enough red blood cells, which is why anemia can make you feel very tired, short of breath, or lightheaded.

You will have blood tests to check for anemia. Treatment is based on your symptoms and on what is causing the anemia, so there can be more than one cause to look at. If you are extremely tired or notice other signs of anemia, tell your doctor—there are treatments that may help. Your healthcare team can explain what is behind your anemia and what options fit your situation.