Quick summary

It's no exaggeration to say that red blood cells are the life force of the body, since they play such an essential role in carrying oxygen from the lungs to the cells. That's why when a patient's red blood count drops, she really feels it -- and shows it. She may be pale, tired, weak, and have trouble catching her breath. Here's what you need to know to understand what's happening and what to do.

Why does breast cancer cause red blood cell (RBC) counts to drop?

• In most cases, it's not the cancer itself but breast cancer treatment that leads to a shortage of red blood cells, also called anemia. Chemotherapy often damages the bone marrow that produces red and white blood cells and platelets, a condition called bone marrow suppression, or myelosuppression. As red blood cells die out, which they do naturally every 120 days or so, the body isn't able to replace them and the red blood count drops.

• Radiation therapy in some locations can damage red blood cell production.

• Blood loss from surgery can also cause or exacerbate anemia.