Cancer therapy can lower your blood cell counts and chemotherapy especially can affect rapidly dividing bone marrow cells. This hinders the marrow’s ability to supply new cells to the blood during treatment and for some time after. White cell counts decrease most quickly, followed by decreases in platelet counts and then red cells.
Some drugs, however, have little or no damaging effect on the marrow. The effects of other drugs can either be reversed once therapy is stopped or may last for several weeks. The severity of the drug therapy’s effects depend on several factors, including:
Whether the marrow has already been damaged by the cancer before treatment
The type and duration of the drugs
Without treatment, low blood counts can cause the following conditions:
Anemia, an iron deficiency caused by low numbers of red cells that can no longer supply an adequate amount of oxygen
Thrombocytopenia, caused by low numbers of platelets, resulting in bleeding and easy bruising
Neutropenia and monocytopenia as a result of too few neutrophils and monocytes (types of white cells), which impair the body’s ability to fight infections
Low numbers of all three blood cell counts is called pancytopenia.
Anemia and Low Red Cell Counts
Anemia is caused by a low red cell count. Its side effects include:
Fatigue or shortness of breath, especially with physical activity
Pale skin, gums or nails
Light-headedness or dizziness
A tendency to feel cold