leukemia, leucemia


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[leuko- + -emia]
Any of a class of hematological malignancies of bone marrow cells in which immortal clones of immature blood cells multiply at the expense of normal blood cells. As normal blood cells are depleted from the body, anemia, infection, hemorrhage, or death result. The leukemias are categorized as chronic or acute; by the cell type from which they originate; and by the genetic, chromosomal, or growth factor aberration present in the malignant cells.
Chronic leukemias, which have a relatively slow course, include chronic lymphocytic (CLL), chronic myelogenous or granulocytic (CML), and hairy cell leukemia (a subtype of CLL). Median survival in these illnesses is about 4 yr.

Acute leukemias include acute lymphocytic (ALL) and acute myeloid (myelogenous) (AML) leukemia. If untreated, these diseases are fatal within weeks or months. Each of these types of leukemia is discussed in subentries, below.

All the different molecular events leading to the development of unchecked cellular reproduction in the leukemias result from genetic or chromosomal lesions in blood-forming cells. Duplications of genetic material (hyperdiploidy), loss of genetic information (hypodiploidy), inactivation of genes that normally suppress tumor development, chromosomal translocations, and the release of abnormal fusion proteins can all cause leukemia. These genetic lesions in turn can be produced by viruses, ionizing radiation, chemotherapeutic drugs, and toxic chemicals. Rarely, leukemias are caused by familial genetic syndromes, e.g., ataxia telangiectasia, Bloom syndrome, or Fanconi syndrome.

Clinical findings such as anemia, fatigue, lethargy, fever, and bone and joint pain may be present. Physical findings include combinations of pallor, petechiae, or purpura; mucous membrane bleeding; enlarged liver, spleen, and kidneys; and tenderness over the sternum and other bones.

Microscopic examination of peripheral blood and specimens of bone marrow are used to establish the diagnosis. These studies are followed by cytochemical and cytogenetic studies of abnormal cells found in the marrow or the peripheral blood to confirm the diagnosis with special stains and chromosomal analysis. Leukemic cells can also be identified by flow cytometry and immunocytochemistry, which rely on antibodies binding to and helping to identify malignant cells. The spread of leukemias to internal organs, e.g., the brain, the kidneys, or the lungs, may be evaluated with imaging tests, e.g., MRI studies, CT scans, or ultrasound.

Chemotherapy, bone marrow transplantation, or both are used to treat leukemias. Regimens are devised regularly and are tailored to specific illnesses. Treatment is often given in several phases, with a period of induction chemotherapy to induce remission by completely eliminating leukemic cells from the bone marrow, followed by consolidation and maintenance phases. This multiphase treatment is designed to further deplete malignant cells from the bone marrow and to achieve complete cure.

Patient care measures focus on eradicating the illness; managing complications; minimizing the effects of chemotherapy; preserving veins (often an indwelling port is inserted to administer chemotherapy); and providing comfort, education, and psychological support. The specific needs of patients (many of whom are children) and their families must be considered. Instruction is provided about drugs the patient will receive, including any adverse reactions and measures that will be taken to prevent or alleviate these effects. Prescribed chemotherapy is administered with special precautions when indicated for infusion and drug disposal. If the chemotherapy causes weight loss or anorexia, nutritional guidance is provided. Oral, skin, and rectal care must be meticulous, e.g., the nurse must thoroughly clean the skin before all invasive procedures, inspect the patient for perirectal erosions, use strict aseptic technique when starting an intravenous line, and change sets, i.e., intravenous tubing and associated equipment, according to chemotherapeutic protocols. Ports are irrigated according to agency protocol. If the patient is receiving intrathecal chemotherapy, the lumbar puncture site is checked frequently for bleeding or oozing. The patient and family are taught to recognize signs of infection (fevers, chills, sore throat, cough, urinary difficulties) and are urged to report these to the oncologist or hematologist promptly. To prevent infection in neutropenic patients, strict hand hygiene protocols, special diets, and (in hospitalized patients) laminar airflow or other reverse isolation measures are instituted. The patient is monitored for bleeding. If bleeding occurs, compresses are applied and the bleeding site is elevated. Transfusions of platelets and other blood cells are often needed. Complications associated with specific chemotherapeutic regimens, e.g., hair loss, nausea and vomiting, anemia, neutropenia, and low platelets, are explained to the patient, along with management strategies that will be employed. Prescribed analgesics are administered as needed, and noninvasive pain relief techniques and comfort measures, e.g., position changes, cutaneous stimulation, distraction, relaxation breathing, and imagery, may be used. Gentle oral hygiene measures and protective skin care are explained. Fluid intake should be increased to eliminate chemotherapy metabolites, and the patient advised to void more frequently to prevent cystitis. Dietary fiber is important, and stool softeners may be used to ensure normal bowel movements. Antidiarrheals usually control diarrhea, but the patient should be monitored for signs of dehydration. Fatigue is an anticipated adverse effect of treatment; therefore the patient is encouraged to alternate activity with rest periods and to obtain assistance with daily activities as necessary. Reproductive issues should be discussed with the patient. Patient care routines and visiting times should be flexible when hospitalization is required. The patient and family are encouraged to participate in care as much as possible. Referrals are made to social service agencies, home health care agencies, and support groups. If the patient does not respond to treatment and has reached the terminal phase of the disease, supportive nursing, palliative care, or hospice care should be discussed sensitively with patients and their caregivers.

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