Neutropenia and cancer
Neutropenia is characterized by a reduced number of neutrophils, the most abundant type of white blood cell, which play a crucial role in the immune response by fighting infections. This condition is particularly relevant for cancer patients, as chemotherapy and radiation therapy can significantly lower neutrophil counts, putting individuals at greater risk for infections. Neutropenia is defined when neutrophil levels fall below 500 cells per cubic millimeter of blood, with symptoms often beginning with fever and potentially leading to serious infections.
Patients with hematologic cancers, such as leukemia and lymphoma, are at heightened risk, as are those undergoing certain cancer treatments. The incidence of neutropenia varies depending on the specific chemotherapy regimen, with around half of all chemotherapy patients developing this condition. Diagnosis typically involves a complete blood count (CBC) to assess neutrophil levels, and treatment focuses on managing infections and may involve medications to stimulate neutrophil production.
Preventive measures include adjusting chemotherapy doses and using colony-stimulating factors for those at higher risk. While neutropenia can pose significant challenges, most cases resolve within weeks after adjusting treatment. Understanding neutropenia's implications is essential for cancer patients and caregivers to navigate the complexities of treatment and infection risk.
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Neutropenia and cancer
ALSO KNOWN AS: Agranulocytosis, granulocytopenia
RELATED CONDITIONS: Leukopenia, aplastic anemia, myelodysplastic syndromes
DEFINITION: Neutropenia is a decreased number of circulating neutrophils, the most abundant type of white blood cell and an essential component of the immune response to infections, especially bacterial or fungal infections. Neutrophils are the first to respond to an infection, ingesting and killing the microorganisms, thus preventing infection or lessening its severity. A patient with a significantly reduced number of neutrophils is at increased risk for infection.
Normal total white blood cell counts range from 5,000 to 10,000 cells per cubic millimeter (mm3) of blood, with neutrophils making up 50 to 70 percent of the circulating white blood cells. Therefore, the normal absolute number of neutrophils is about 2,500 to 7,000 neutrophils/mm3 of blood. People are considered to have neutropenia when levels drop below 500 neutrophils/mm3 of blood.
Risk factors: Because most chemotherapeutic agents work to kill fast-growing cells, including neutrophils, almost all cancer patients are at risk for neutropenia. Radiation therapy for cancer treatment can also cause neutropenia. Other factors, including age, nutritional status, and previous exposure to chemotherapy or radiation, increase the risk of neutropenia in someone undergoing chemotherapy or radiation therapy. Patients with hematologic cancers, such as leukemias or lymphomas, are also at increased risk for neutropenia.
Etiology and the disease process: Neutropenia may be caused by several infections, conditions, and disorders, including myelodysplastic syndromes (MDS), COVID-19, Epstein-Barr virus (EBV), HIV, hepatitis, rheumatoid arthritis (RA), or lupus. Nutrition deficiencies also play a role. In patients with certain cancers or those undergoing some cancer treatments, the risk of developing neutropenia is higher. These cancers include leukemia, lymphoma, and multiple myeloma, and treatments include chemotherapy, targeted drug therapy, bone marrow transplants, or stem cell transplants. Most anticancer drugs work to disrupt the growth of cancer cells, which tend to grow very quickly. These drugs target cell components involved in cell division and deoxyribonucleic acid (DNA) synthesis. As a result, the drugs may affect other fast-growing cells in the body, including the cells of the bone marrow that are precursors to blood cells. Neutrophils are short-lived (surviving two to three days) in the body, with millions of new neutrophils released every minute from the bone marrow. Therefore, the bone marrow cells rapidly dividing to make new neutrophils are at high risk for damage from anticancer agents.
Radiation therapy can cause neutropenia if the targeted treatment area includes bones that contain productive marrow (not all marrow actively produces blood cells). Additionally, patients who need a bone marrow transplant must have the diseased bone marrow completely destroyed before the transplant.
Incidence: Chemotherapy is the most common cause of neutropenia, but its incidence among patients varies. In total, around half of all patients receiving chemotherapy will develop neutropenia. Each drug and drug combination causes neutropenia at a different rate. For example, the cisplatin/fluorouracil combination used to treat head and neck cancers has been shown to cause neutropenia in a small percentage of patients. Cisplatin combined with gemcitabine to treat bladder cancer causes neutropenia in around 70 percent of patients. The other risk factors, such as age, also contribute to the different incidence rates.
Symptoms: Because low neutrophil counts predispose patients to infection, the first symptom is usually fever, followed by symptoms specific to the infection, including a cough, a sore throat, bronchitis, sinusitis, pneumonia, gingivitis, sores around the mouth and anus, fatigue, and frequent or unusual infections.
Screening and diagnosis: A complete blood count (CBC) with differential tests for levels of the different types of cells in the blood can screen for neutropenia. The differential portion of the test tells the percentage of each type of white blood cell, including the percentage of neutrophils. From this, the absolute number of neutrophils/mm3 can be calculated to determine if a patient is neutropenic and at risk for infection. Patients with borderline levels at 500 to 1,500 cells/mm3 have a slight-to-moderate risk of infection, while patients with counts below 500 cells/mm3 (neutropenic) have a severe risk of infection.
Treatment and therapy: The priority of treatment is to address fever and underlying infection. Antibiotics or antifungals are necessary to treat the infection. The patient may also require granulocyte-macrophage colony-stimulating factor (GM-CSF) or granulocyte colony-stimulating factor (G-CSF). These drugs stimulate the bone marrow to increase the production of neutrophils and are used following chemotherapy and bone marrow transplantation. Additionally, changes in the chemotherapy regimen may be necessary. The physician may choose to lower the dose of medication, remove a drug from the regimen, or change the most harmful drug to a less toxic drug.
Prognosis, prevention, and outcomes: A neutropenic cancer patient who acquires an infection has a mortality rate of 4 to 30 percent. To prevent neutropenia in cancer patients receiving treatment, doctors can lower the dose of chemotherapy for patients who have a documented history of neutropenia. Doctors can also use colony-stimulating factors in patients at higher risk for neutropenia, such as when a treatment regimen is known to cause neutropenia in a high percentage (greater than 40 percent) of patients. Most cases of chemotherapy-induced neutropenia resolve within two weeks of discontinuing drug treatment.
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