White blood cells, also known as leukocytes, are essential components of the body’s immune system, fighting off infections. While breast cancer itself rarely causes a significant drop in these protective cells, its treatments are a common cause of reduced white blood cell counts. Understanding this connection is important for patients undergoing breast cancer treatment, as a low count can increase the risk of infection and impact overall well-being during therapy.
Understanding White Blood Cells and Low Count
White blood cells are a diverse group of cells, each with specialized roles in the immune response. Among these, neutrophils are particularly important, serving as the body’s primary defense against many bacterial and fungal infections. A low white blood cell count, medically termed leukopenia, indicates a reduced number of these protective cells in the bloodstream. When specifically referring to a low neutrophil count, the condition is called neutropenia. Neutropenia is often defined as having fewer than 1,500 neutrophils per microliter of blood. Severe neutropenia occurs when the count drops below 500 neutrophils per microliter, significantly increasing the risk of serious infections.
Causes of Low White Blood Cell Count in Breast Cancer Patients
Breast cancer rarely causes a low white blood cell count unless it spreads to the bone marrow, where blood cells are produced. However, the primary reasons for reduced white blood cell counts in breast cancer patients are typically related to the treatments used to combat the disease. These therapies often target rapidly dividing cells, which unfortunately include healthy cells in the bone marrow responsible for producing white blood cells.
Chemotherapy is a major contributor to low white blood cell counts. Chemotherapy drugs are designed to kill fast-growing cancer cells, but they also affect other rapidly dividing cells in the body, such as those in the bone marrow. This suppression of bone marrow activity leads to a decrease in the production of white blood cells. The lowest point of the white blood cell count after chemotherapy, known as the “nadir,” typically occurs about 7 to 14 days after a treatment session. This period marks the highest risk for infection.
Radiation therapy can also lead to reduced white blood cell counts, especially when large areas of bone marrow are included in the treated field. Radiation damages the stem cells in the bone marrow, impairing their ability to produce new blood cells. Some newer treatments, such as certain targeted therapies or immunotherapies, may also have an impact on white blood cell counts, though less commonly than chemotherapy. These therapies can alter the immune system’s function, potentially increasing the risk of infection or directly affecting blood cell production. Additionally, other non-cancer-related factors like certain infections or other medications can contribute to a low white blood cell count in cancer patients.
Managing Low White Blood Cell Count and Its Risks
The main concern associated with a low white blood cell count, particularly neutropenia, is a heightened susceptibility to serious infections. With fewer neutrophils available to fight off pathogens, the body becomes vulnerable to bacteria, viruses, and fungi that it would normally easily manage. Even common bacteria residing in the mouth or gut can cause significant illness when neutrophil levels are severely low.
Patients with low white blood cell counts should be vigilant for signs of infection, which may include fever, chills, sweats, sore throat, mouth sores, or new pain. A fever, defined as a temperature over 100.4°F (38°C), requires immediate medical attention. Prompt reporting of these symptoms is important, as infections can rapidly become severe in individuals with compromised immunity.
Healthcare providers closely monitor white blood cell counts through regular blood tests, often as part of a complete blood count (CBC), throughout cancer treatment. This monitoring helps determine when counts are low and when interventions are necessary. If counts drop significantly, treatment may be delayed to allow the bone marrow to recover.
Several strategies help manage low white blood cell counts and reduce infection risk. Patients are often advised to practice meticulous hand hygiene, avoid large crowds, and limit contact with sick individuals. Proper food safety practices are also recommended to prevent foodborne illnesses. Medical interventions include the use of growth factors, such as granulocyte colony-stimulating factors (G-CSFs), which stimulate the bone marrow to produce more white blood cells, typically given as injections after chemotherapy. Antibiotics are frequently prescribed for suspected or confirmed infections to prevent or treat serious complications.