Overview

Leukemia is a cancer of the blood cells. Blood cells (including red cells that carry oxygen, white cells to fight infection, and platelets that cause blood to clot) are produced in the bone marrow, the spongy tissue inside the larger bones in the body. Abnormalities in the bone marrow cells can cause the overproduction or underproduction of certain blood cells. Eosinophilia is a condition where the bone marrow makes too many eosinophils, a type of blood cell that is involved in allergic reactions or used to fight certain parasites.

Primary eosinophilia is an increased number of eosinophils. It can be clonal eosinophilia (from an acquired genetic abnormality) or idiopathic hypereosinophilia (from an unknown cause). Chronic eosinophilic leukemia is a subtype of clonal eosinophilia that is sometimes called hypereosinophilic syndrome (HES).

Some people can also have high numbers of eosinophils without having cancer. For example, sometimes the body makes too many eosinophils in response to an allergen or a parasite. This type of eosinophilia is called secondary eosinophilia. Secondary eosinophilia, the reaction to a disease or parasite, is more common than eosinophilic leukemia.

Risk Factors

A risk factor is anything that increases a person's chance of developing cancer. Some risk factors can be controlled, such as smoking, and some cannot be controlled, such as age and family history. Although risk factors can influence the development of cancer, most do not directly cause cancer. Some people with several risk factors never develop cancer, while others with no known risk factors do. However, knowing your risk factors and communicating them to your doctor may help you make more informed lifestyle and health-care choices.

Leukemia can be caused by a genetic mutation brought on by heredity or environmental factors (including smoking, chemical or radiation exposure). However, many cases of leukemia have unknown causes. The specific cause of eosinophilic leukemia is not known.

Symptoms

People with eosinophilic leukemia may experience the following symptoms. Sometimes, people with eosinophilic leukemia do not show any of these symptoms. Or, these symptoms may be caused by a medical condition that is not cancer. If you are concerned about a symptom on this list, please talk with your doctor.

• Fever
• Fatigue
• Cough
• Swollen lymph nodes
• Muscle pains
• Pruritus (itching)
• Diarrhea

Diagnosis

Doctors use many tests, such as blood tests and bone marrow tests, to diagnose eosinophilia. Although a patient's signs and symptoms may cause a doctor to suspect eosinophilia, it is diagnosed only by blood tests and bone marrow evaluations. Some tests may also determine which treatments may be the most effective. Your doctor may consider these factors when choosing a diagnostic test:

• Age and medical condition
• The type of cancer
• Severity of symptoms
• Previous test results

The main criteria for diagnosing eosinophilic leukemia are:

• An eosinophil count in the blood greater than or equal to 1.5 x 109 L
• The absence of parasitic, allergic, or other causes of eosinophilia
• Organ system involvement or dysfunction directly related to eosinophilia

Blood tests. The diagnosis of eosinophilic leukemia begins with a routine blood test to measure the counts of different types of cells in a person's blood. If the blood contains high levels of eosinophils, eosinophilic leukemia may be present.

Bone marrow biopsy. In a bone marrow biopsy, a doctor takes a sample of marrow, usually from the back of the hipbone, with a needle. The cells from the marrow, along with the cells from the blood, are analyzed by a pathologist (a doctor who specializes in interpreting laboratory tests and evaluating cells, tissues, and organs to diagnose disease) for the sample percentage of the immature cells, known as blasts. This percentage tells the doctor whether the disease is acute or chronic eosinophilic leukemia.

Immunophenotyping. Immunophenotyping is the examination of the antigens (proteins) on the surface of the leukemic cells and allows the doctor to confirm the exact type of leukemia.

Cytogenetics. Cytogenetics is the examination of the leukemic cells for chromosomal abnormalities. It assists in confirming the diagnosis and may help the doctor determine the person's prognosis (chance of recovery).

Computed tomography (CT or CAT) scan. A CT scan creates a three-dimensional picture of the inside of the body with an x-ray machine. A computer then puts these images into a detailed, cross-sectional view that shows any abnormalities or tumors. Sometimes, a contrast medium (a special dye) is injected into a vein to provide better detail. A CT scan also shows enlarged lymph nodes or a swollen spleen.

Cardiac evaluation. People with higher eosinophil counts over a longer period frequently have disturbances in heart function and rhythm. Therefore, an electrocardiogram (ECG or EKG, a test that records the electrical activity of the heart to show abnormal rhythms or detect damage) and an echocardiogram (a procedure that evaluates the structure and function of the heart using sound waves and an electronic sensor) are often recommended.

Treatment

The treatment of eosinophilic leukemia depends on various factors. In many cases, a team of doctors will work with the patient to determine the best treatment plan.

According to the National Cancer Institute, the best treatment for eosinophilic leukemia remains unclear. People are encouraged to enroll in clinical trials designed to evaluate new treatments. See the Clinical Trials Resources section for more information.

General treatments for myeloproliferative (myelo- refers to bone marrow, proliferative means excess) disorders, such as eosinophilic leukemia, include chemotherapy, radiation therapy, surgery, and biologic therapies. Usually, myeloproliferative disorders cannot be cured, but treatment helps to control the symptoms.

Chemotherapy

Chemotherapy is the use of drugs to kill cancer cells. Chemotherapy travels through the bloodstream to cancer cells throughout the body. Chemotherapy can be given by mouth or injection.

Because chemotherapy affects normal cells as well as cancer cells, many people experience side effects from treatment. Side effects depend on the drug and the dosage. Common side effects include nausea and vomiting, loss of appetite, diarrhea, fatigue, low blood count, bleeding or bruising after minor cuts or injuries, numbness and tingling in the hands or feet, headaches, hair loss, and darkening of the skin and fingernails. Side effects usually go away when treatment is complete.

Some chemotherapy agents that are used in treating eosinophilic leukemia include hydroxyurea (Hydrea, Droxia), cyclophosphamide (Cytoxan, Neosar), and vincristine (Oncovin).

The medications used to treat cancer are continually being evaluated. Talking with your doctor is often the best way to learn about the medications you've been prescribed, their purpose, and their potential side effects or interactions with other medications. Learn more about your prescriptions through PLWC's Drug Information Resources, which provides links to searchable drug databases.

Radiation therapy

Radiation therapy uses high-energy x-rays or other particles to kill cancer cells. The most common type of radiation therapy is called external-beam radiation therapy, which is radiation given from a machine outside the body. When radiation therapy is given using implants, it is called internal radiation therapy or brachytherapy. Radiation therapy for eosinophilic leukemia is generally used as a palliative treatment (care given to improve quality of life by treating symptoms and side effects of the cancer or its treatment).

Side effects from radiation therapy include tiredness, mild skin reactions, upset stomach, and loose bowel movements. Most side effects go away soon after treatment is finished.

Surgery

Surgery to remove the spleen (splenectomy), which also produces white blood cells, may occasionally be performed.

Biologic therapy

Biologic therapy, or immunotherapy, employs the body to fight the cancer by supplying a substance to boost the body's natural defenses. Interferon-alpha (Roferon, Intron A) is a biologic therapy that is occasionally used to treat eosinophilic leukemia.

Targeted therapy

Imatinib (Gleevec) may be useful for some patients. In many patients, the leukemic cells have a specific genetic abnormality (platelet derived growth factor receptor [PDGFR] mutation) that produces a protein that stimulates the cells to grow. Imatinib kills the abnormal eosinophils by blocking the function of this protein. Imatinib is more likely to work if this mutation is present; however, if the mutation is not present, there is still a possibility that the disease would respond to the drug. The main side effects of imatinib include the following:

• Swelling around the eyes
• Leg swelling
• Headache
• Fatigue
• Rash
• Musculoskeletal pain
• Leg cramping

Steroids

Steroids are used to control some symptoms of the disease and are usually prescribed for certain conditions, such as a high white blood cell count.

Hematopoietic stem cell transplantation

Hematopoietic stem cells are special cells that can develop into different kinds of blood cells, such as red blood cells, white blood cells, or platelets. Stem cells are found both in the circulating blood and in the bone marrow. In a stem cell transplantation (SCT), the person is first treated with high doses of chemotherapy and/or radiation therapy to get rid of as many cancer (leukemic) cells as possible and to prevent the immune system from reacting to and rejecting the donated stem cells. After the high-dose therapy is given, stem cells obtained from a healthy donor (usually a sibling) are infused into the patient's bloodstream. Within two to three weeks, these cells will mature into healthy, blood-producing tissue. Until that time, people may need antibiotics to prevent and treat infection and transfusions of red blood cells and platelets.

This type of SCT is called an allogeneic SCT, because the new stem cells came from a donor. Allogeneic transplantation may be a considered a good treatment option in some patients, especially those who are younger.

An autologous transplantation is the use of the person's own stem cells. The blood or bone marrow stem cells are removed from the person when he or she is in complete remission and then frozen. The person then receives the same treatment given for an allogeneic transplantation, and the frozen stem cells are thawed and injected back into the bloodstream to replace the destroyed marrow. This type of transplant is rarely considered for patients with eosinophilic leukemia.

SCT is a higher-risk procedure and is not used frequently in people with eosinophilic leukemia because it is sometimes not a consistently effective therapy and because many patients with this disease are older and may not tolerate the therapy well.

Side Effects of Cancer and Cancer Treatment

Cancer and cancer treatment can cause a variety of side effects; some are easily controlled and others require specialized care. Below are some of the side effects that are more common to eosinophilic leukemia and its treatments. For more detailed information on managing these and other side effects of cancer and cancer treatment, visit the PLWC Managing Side Effects section.

Constipation. Constipation is the infrequent or difficult passage of stool. About 40% of patients in palliative care (care given to improve a patient's quality of life) experience constipation, and about 90% of patients taking opioid medications (such as morphine) experience constipation. Constipation includes fewer bowel movements, stools that are abnormally hard, discomfort, or a feeling of incomplete rectal emptying. Patients with constipation can experience pain, swelling in the abdomen, loss of appetite, nausea and/or vomiting, inability to urinate, and confusion.

Fatigue (tiredness). Fatigue is extreme exhaustion or tiredness, and is the most common problem that people with cancer experience. More than half of patients experience fatigue during chemotherapy or radiation therapy, and up to 70% of patients with advanced cancer experience fatigue. Patients who feel fatigue often say that even a small effort, such as walking across a room, can seem like too much. Fatigue can seriously affect family activities and other daily activities, can make patients avoid or skip cancer treatments, and may even affect the will to live.

Hair loss (alopecia). A potential side effect of radiation therapy and chemotherapy is hair loss. Radiation therapy and chemotherapy cause hair loss by damaging the hair follicles responsible for hair growth. Hair loss may occur throughout the body, including the head, face, arms, legs, underarms, and pubic area. The hair may fall out entirely, gradually, or in sections. In some cases, the hair will simply thin-sometimes unnoticeably-and may become duller and dryer. Losing one's hair can be a psychologically and emotionally challenging experience and can affect a patient's self-image and quality of life. However, the hair loss is usually temporary, and the hair often grows back.

Mouth sores (mucositis). Mucositis is an inflammation of the inside of the mouth and throat, leading to painful ulcers and mouth sores. It occurs in up to 40% of patients receiving chemotherapy treatments. Mucositis can be caused by chemotherapy directly, the reduced immunity brought on by chemotherapy, or radiation therapy to the head and neck area.

Nausea and vomiting. Vomiting, also called emesis or throwing up, is the act of expelling the contents of the stomach through the mouth. It is a natural way for the body to rid itself of harmful substances. Nausea is the urge to vomit. Nausea and vomiting are preventable, treatable side effects. They are common in patients receiving chemotherapy for cancer and in some patients receiving radiation therapy. Many patients with cancer say they fear nausea and vomiting more than any other side effects of treatment. When it is minor and treated quickly, nausea and vomiting can be quite uncomfortable but cause no serious problems. Persistent vomiting can cause dehydration, electrolyte imbalance, weight loss, depression, and avoidance of chemotherapy.

Neutropenia. Neutropenia is an abnormally low level of neutrophils, a type of white blood cell. All white blood cells help the body fight infection. Neutrophils fight infection by destroying bacteria. Patients who have neutropenia are at increased risk for developing serious bacterial infections because there are not enough neutrophils to destroy harmful bacteria. Neutropenia occurs in about 50% of patients receiving chemotherapy and is common in patients with leukemia.

Skin problems. The skin is an organ system that contains many nerves. Skin problems can be very painful, difficult to cope with, and often lead to other serious problems. As with other side effects, prevention or early treatment is best. In other cases, treatment and wound care can often improve pain and quality of life. Skin problems can have many different causes, including chemotherapy leaking out of the intravenous (IV) tube, which can cause pain or burning; peeling or burned skin caused by radiation therapy; pressure ulcers (bed sores) caused by constant pressure on one area of the body; and pruritus (itching) in patients with cancer, most often caused by leukemia, lymphoma, myeloma, or other cancers.

Thrombocytopenia. Thrombocytopenia is an unusually low level of platelets (thrombocytes) in the blood. Platelets are the blood cells that stop bleeding by plugging damaged blood vessels and helping the blood to clot. Patients with low levels of platelets bleed more easily and are prone to bruising. Certain types of chemotherapy can damage the bone marrow so that it does not make enough platelets. Thrombocytopenia caused by chemotherapy is usually temporary. Other medications used to treat cancer may also lower the number of platelets. In rare instances, a patient's body can make antibodies to the platelets, lowering the number of platelets.

After Treatment

After treatment for eosinophilic leukemia ends, talk with your doctor about developing a follow-up care plan. This plan may include regular physical examinations, blood tests, bone marrow biopsies, and possibly scans or other imaging studies to monitor your recovery for the coming months and years. People experiencing a long-term remission are encouraged to follow cancer screening recommendations for the general population.

Some cancer treatments may cause long-term side effects.

• Numbness, tingling, and pain in the hands and feet may occur in people who have received vincristine.
• Cardiac damage in the form of a weakened heart muscle may occur in people who have received a higher total dose of doxorubicin (Adriamycin) or radiation therapy to the chest.
• Infertility or premature menopause can occur in people who have received high-dose cyclophosphamide or other chemotherapy.
• Secondary leukemia and secondary cancers (cancers that develop because of the treatment for another type of cancer) are more common in people who were treated with chemotherapy and radiation therapy.

Talk with your doctor or health-care team about the best ways to manage these side effects.