The relationship between low blood cell counts and cancer can be a result of cancer treatment such as chemotherapy or radiation, according to Mayo Clinic. However, types of cancer such as blood or bone marrow cancers, along with cancers that spread to other parts of the body, can also affect blood cell counts because normal amounts of blood cells cannot develop.
A low blood cell count during chemotherapy treatment can be due to chemotherapy damaging a person's bone marrow, states Mayo Clinic. The bone marrow in a person's body is responsible for making blood cells. These cells grow rapidly, which causes them to be affected by chemotherapy. While some types of chemotherapy treatment can damage blood cells, they do recover.
A person who receives radiation therapy during cancer treatment may also experience low levels of both red and white blood cells, notes Mayo Clinic. This can occur when large areas of the body are treated with radiation or bones in the pelvis, legs or torso are treated. This occurs because these large bones produce the largest amount of bone marrow.
Monitoring the levels of a cancer patent's blood cell counts is vital during treatment, as a low level can result in medical issues or a delay in treatment, according to Mayo Clinic. When the white blood cells that fight infection are too low, the body can no longer fight off infection. This can mean treatment must be stopped until levels return to an acceptable level. Anemia occurs when a person has too few red blood cells, causing fatigue and shortness of breath. This can also cause a delay in cancer treatment, although this condition can be treated with a transfusion.