The term “neutropenia” refers to an unusually low number of neutrophils, a type of infection-fighting white blood cell. Because neutrophils are short-lived, the body produces about 100 billion of these cells every day. They play a key role in maintaining good health by seeking out and destroying harmful bacteria.
Chemotherapy can reduce the number of neutrophils in the blood, which can lead to fever (febrile neutropenia), as well as infections—some of which can be serious and life-threatening. Doctors rate the severity of neutropenia based on the number of neutrophils per microliter of blood (one-millionth of a liter, or quart). A blood test measures the neutrophil count: 1,700 per microliter or above is considered normal; 1,000 to 1,500 is mild neutropenia; 500 to 1,000 is moderate; less than 500 is severe. The risk of infections rises when neutropenia is more severe and long-lasting.
Neutrophil counts usually start to drop about a week after each round of chemotherapy begins. They often reach a low point (called the nadir) about seven to 14 days after treatment. This is when infections are more likely to develop. The neutrophil count starts to rise again as the bone marrow resumes its normal production of neutrophils. It can take as long as three to four weeks to reach a normal level again.
If neutropenia develops or the neutrophil level does not return to normal quickly enough, a doctor may postpone the next round of chemotherapy or recommend a lower dose.
People who receive standard chemotherapy treatments for most solid tumors such as breast or lung cancer have a lower risk of developing neutropenia than do those with leukemia or lymphomas. But it’s important for all people with cancer to be aware of this side effect and to work closely with their health care team to prevent and treat it effectively. After a chemotherapy session, call your doctor or nurse if you notice any of these side effects of chemotherapy:
• Fever (body temperature above 101ºF)
• Sore mouth or gums
• Pain or swelling in the gums
• Swollen, inflamed or pus-filled skin sores
• Sinus or ear infections
• Cough and shortness of breath with fever
• Irritation in and around the anus
Doctors use three main types of medications to treat the effects of neutropenia: antibiotics for bacterial infections; antifungal drugs for fungal infections found in the throat or lungs, for example; and colony-stimulating factors (CSFs) to raise the number of white blood cells. For some people, continual use of antibiotics or antifungals as a preventive measure may be beneficial.
CSFs are used both to treat neutropenia and prevent it if a person is at increased risk of developing the condition after receiving chemotherapy. They work by stimulating the bone marrow to produce more white blood cells.