Leukemia , also spelled leukemia , is a group of cancers that usually begin in the bone marrow and produce abnormally high white blood cells. These white blood cells are not fully developed and are called blast cells or leukemia cells. Symptoms may include bleeding and bruising problems, fatigue, fever, and increased risk of infection. These symptoms occur because of the lack of normal blood cells. Diagnosis is usually done with a blood test or bone marrow biopsy.
The exact cause of leukemia is unknown. The combination of genetic factors and environmental factors (which are not inherited) is believed to play a role. Risk factors include smoking, ionizing radiation, some chemicals (such as benzene), previous chemotherapy, and Down syndrome. People with a family history of leukemia are also at higher risk. There are four major types of leukemia - acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), chronic lymphocytic leukemia (CLL) and chronic myeloid leukemia (CML) - as well as a less common number. Leukemia and lymphomas are both derived from a wider tumor group that affects the blood, bone marrow, and lymphoid system, known as hematopoietic and lymphoid tissue tumors.
Treatment may involve several combinations of chemotherapy, radiation therapy, targeted therapy, and bone marrow transplantation, in addition to supportive care and palliative care as needed. Certain types of leukemia can be managed by waiting alert. The success of treatment depends on the type of leukemia and the age of the person. Results have increased in developed countries. The average five-year survival rate is 57% in the United States. In children under 15 years, the five-year survival rate is greater than 60 to 85%, depending on the type of leukemia. In children with acute cancer-free acute leukemia after five years, cancer is unlikely to return.
By 2015, leukemia is present in 2.3 million people and causes 353,500 deaths. In 2012 this newly developed in 352,000 people. This is the most common type of cancer in children, with three-quarters of cases of leukemia in children being an acute lymphoblastic type. However, about 90% of all leukemia is diagnosed in adults, with AML and CLL being most common in adults. It happens more commonly in developed countries.
Video Leukemia
Classification
General classification
Clinically and pathologically, leukemia is divided into large groups. The first division is between the acute and chronic form:
- Acute leukemia is characterized by a rapid increase in the number of immature blood cells. The crowd generated from these cells makes the bone marrow unable to produce healthy blood cells. Immediate treatment is necessary in acute leukemia due to the rapid development and accumulation of malignant cells, which then spread to the bloodstream and spread to other organs. This form of acute leukemia is the most common form of leukemia in children.
- Chronic leukemia is characterized by an overcrowding of relatively mature white blood cells, but still abnormal. It usually takes months or years to progress, cells are produced at a much higher rate than normal, producing abnormal white blood cells. While acute leukemia should be treated promptly, chronic forms are sometimes monitored for some time before treatment to ensure maximum therapeutic effectiveness. Chronic leukemia occurs mostly in the elderly, but can occur in all age groups.
In addition, the disease is subdivided according to the type of blood cell affected. This divides leukemia into lymphoblastic or lymphocytic leukemia and myeloid or myelogenous leukemia :
- In lymphoblastic or lymphocytic leukemia, cancerous changes occur in a type of marrow cell that normally forms lymphocytes, which are immune cells that fight infection. Most lymphocytic leukemia involves a specific lymphocyte subtype, B cell.
- In myelogenous or myeloid leukemia, cancer changes occur in the type of marrow cells that normally form red blood cells, some types of white blood cells, and platelets.
Combining these two classifications gives a total of four main categories. Within each of these major categories, there are usually several sub-categories. Finally, some of the less common types are usually considered to be outside of this classification scheme.
Specific type
- Acute lymphoblastic leukemia (ALL) is the most common type of leukemia in young children. It also affects adults, especially those aged 65 years and over. Standard treatments include chemotherapy and radiotherapy. Survival rates vary by age: 85% in children and 50% in adults. Subtypes include precursors B acute lymphoblastic leukemia, acute lymphoblastic leukemia T leukemia, Burkitt leukemia, and acute biphenotypic leukemia.
- Chronic lymphocytic leukemia (CLL) most commonly affects adults over the age of 55 years. Sometimes it occurs in younger adults, but almost never occurs in children. Two thirds of people affected are men. The five-year survival rate is 75%. It can not be cured, but there are many effective treatments. One subtype is B-cell prolymphocytic leukemia, a more aggressive disease.
- Acute myelogenous leukemia (AML) occurs more frequently in adults than in children, and more often in men than in women. It is treated with chemotherapy. The five-year survival rate is 40%, except for APL (Acute Promyelocytic Leukemia), which has a survival rate greater than 90%. The AML subtype includes acute promyelocytic leukemia, acute myeloblastic leukemia, and acute megakaryoblastic leukemia.
- Chronic myelogenous leukemia (CML) occurs mainly in adults; a small number of children also develop this disease. It is treated with imatinib (Gleevec in the United States, Glivec in Europe) or other medicines. The five-year survival rate is 90%. One subtype is chronic myelomonocytic leukemia.
- Hair-cell leukemia (HCL) is sometimes considered to be part of chronic lymphocytic leukemia, but does not fit into this category. About 80% of affected people are adult males. No cases in children were reported. HCL can not be cured but it is easily treated. Survival is 96% to 100% at ten years.
- T-cell prolymphocytic leukemia (T-PLL) is a very rare and aggressive leukemia that affects adults; more men than women who are diagnosed with this disease. Despite its overall scarcity, it is the most common type of mature T cell leukemia; almost all other leukemia involve B cells. It is difficult to treat, and the average survival is measured in months.
- Large granular lymphocytic leukemia may involve T-cell or NK cells; like hairy cell leukemia, which involves only B cells, it is rare and insolent leukemia (not aggressive).
- Adult T-cell leukemia is caused by human T-lymphotropic (HTLV) virus, a virus similar to HIV. Like HIV, HTLV infects CD4 cells and replicates in them; However, unlike HIV, it does not destroy it. In contrast, HTLV "perpetuates" infected T cells, giving them the ability to proliferate abnormally. Human T-cell lymphotropic virus types I and II (HTLV-I/II) are endemic in certain areas of the world. Clonal eosinophilias (or clonal hypereosinophilia) is a group of haematological disorders characterized by the development and growth of pre-malignant or malignant eosinophil populations in bone marrow, blood, and/or other tissues. This population consists of an eosinophil replica, a group of genetically identical eosinophils derived from a well-mutated ancestral cell. This disorder can evolve into chronic eosinophilic leukemia or may be associated with various forms of myeloid neoplasm, lymphoid neoplasm, myelofibrosis, or myelodysplastic syndrome.
Maps Leukemia
Signs and symptoms
The most common symptoms in children are easy bruising, pale skin, fever, and an enlarged liver or heart.
Damage to the bone marrow, by shifting normal bone marrow cells to a larger number of white blood cells, results in a lack of blood platelets, which are important in the blood clotting process. This means people with leukemia can easily become bruised, bleed excessively, or develop a pinch (petechiae).
White blood cells, which are involved in combating pathogens, can be suppressed or dysfunctional. This can cause the patient's immune system to be unable to fight a simple infection or start attacking other body cells. Because leukemia prevents the immune system from working normally, some patients experience frequent infections, ranging from infected tonsils, mouth sores, or diarrhea to life-threatening pneumonia or opportunistic infections.
Finally, red blood cell deficiency causes anemia, which can lead to dyspnea and pallor.
Some patients experience other symptoms, such as pain, fever, chills, night sweats, fatigue and other flu-like symptoms. Some patients experience nausea or feelings of satiety because the liver and spleen are enlarged; this can lead to unintentional weight loss. Splashes that are affected by the disease can coalesce and become swollen in the liver or in the lymph nodes causing pain and causing nausea.
If leukemia cells attack the central nervous system, then neurological symptoms (especially headaches) may occur. Unusual neurological symptoms such as migraine, seizures, or coma may occur as a result of brainstem pressure. All the symptoms associated with leukemia can be attributed to other diseases. As a result, leukemia is always diagnosed through medical tests.
The word leukemia , which means 'white blood', is derived from the typical white blood cell count present in most patients before treatment. A high white blood cell count is seen when a blood sample is seen under a microscope, with extra white blood cells often becoming immature or dysfunctional. Excessive cell numbers can also interfere with other cell levels, leading to further imbalances in blood counts.
Some leukemia patients do not have high white blood cell counts seen during regular blood counts. This less common condition is called aleukemia . Bone marrow still contains white blood cancer cells that interfere with the normal production of blood cells, but they remain in the marrow instead of entering the bloodstream, where they will be seen in blood tests. For an aleukemic sufferer, the number of white blood cells in the bloodstream can be normal or low. Aleukemia can occur in one of the four main types of leukemia, and is very common in hairy leukemia cells.
Cause
There is no known single cause for different types of leukemia. Some of the known causes, which are generally not factors in the average control of people, account for relatively few cases. The cause for most cases of leukemia is unknown. Different leukemia may have different causes.
Leukemia, like other cancers, results from mutations in DNA. Certain mutations can trigger leukemia by activating oncogenes or deactivating tumor suppressor genes, and thus disrupting the cell death, differentiation or division arrangements. These mutations may occur spontaneously or as a result of exposure to radiation or carcinogenic substances.
Among adults, known causes are natural and artificial ionizing radiation, some viruses such as human T-lymphotropic virus, and some chemicals, especially benzene and alkylated chemotherapy agents for previous malignancies. Tobacco use is associated with a small increase in the risk of developing acute myeloid leukemia in adults. Cohort studies and case controls have linked exposure to some petrochemicals and hair dyes for the development of some forms of leukemia. Diet has a very limited or no effect, although eating more vegetables may offer little protection benefits.
Viruses have also been linked to some forms of leukemia. For example, the human T-lymphotropic virus (HTLV-1) causes adult T-cell leukemia.
Some cases of mother-fetal transmission (infants acquiring leukemia due to their mother having leukemia during pregnancy) have been reported. Children born to mothers who use fertility drugs to induce ovulation are more than twice as likely to develop leukemia during their childhood than other children.
Radiation
Large doses of Sr-90 emissions from nuclear reactors, seekers of nicknamed bones increase the risk of bone cancers and leukemia in animals, and are considered to do so in humans.
Genetic Condition
Some people have a genetic predisposition to the development of leukemia. This predisposition is shown by family history and twin studies. The affected person may have a single gene or some of the same genes. In some cases, families tend to develop the same type of leukemia with other members; in other families, the affected person may develop various forms of leukemia or blood related cancer.
In addition to this genetic problem, people with chromosomal abnormalities or certain other genetic conditions have a greater risk of leukemia. For example, people with Down syndrome have a significantly increased risk of developing acute leukemia forms (especially acute myeloid leukemia), and Fanconi anemia is a risk factor for developing acute myeloid leukemia. Mutations in the SPRED1 gene have been associated with a predisposition of leukemia in childhood.
Chronic myelogenous leukemia is associated with a genetic disorder called a Philadelphia translocation; 95% of people with CML carry a Philadelphia mutation, although this is not exclusive to CML and can be observed in people with other types of leukemia.
Non-ionizing radiation
Whether non-ionization radiation causes leukemia has been studied for decades. The International Research Agency for the cancer expert working group conducts a detailed review of all the data on static and very low frequency electromagnetic energy, which occurs naturally and in relation to the generation, transmission, and use of electrical power. They conclude that there is limited evidence that high levels of ELF (but not electricity) magnetic fields may cause some cases of leukemia in childhood. There is no evidence for association with leukemia or other forms of malignancy in adults has been demonstrated. Because exposure to these ELFs levels is relatively uncommon, the World Health Organization concludes that ELF exposure, if later proven to be the cause, will reach only 100 to 2400 cases worldwide each year, representing 0.2 to 4.9% of total childhood incidence -little leukemia for that year (about 0.03 to 0.9% of all leukemia).
Diagnosis
The diagnosis is usually based on the total recurrent blood count and bone marrow examination after symptom observation. Occasionally, a blood test may not show that a person has leukemia, especially in the early stages of the disease or during remission. Lymph node biopsy may be performed to diagnose certain types of leukemia in certain situations.
After diagnosis, blood chemistry tests can be used to determine the extent of liver and kidney damage or the effects of chemotherapy in patients. When concerns arise about other damage due to leukemia, doctors may use X-ray, MRI, or ultrasound. It can potentially show leukemia effects on body parts such as bone (X-ray), brain (MRI), or kidney, spleen, and liver (ultrasound). CT scans can be used to check lymph nodes in the chest, although this is rare.
Although using this method to diagnose whether the patient has leukemia, many people have not been diagnosed because many symptoms are vague, non-specific, and can refer to other diseases. For this reason, the American Cancer Society estimates that at least a fifth of people with leukemia have not been diagnosed.
Treatment
Most forms of leukemia are treated with pharmaceutical drugs, usually in combination with multi-drug chemotherapy regimens. Some are also treated with radiation therapy. In some cases, bone marrow transplant is effective.
Acute Lymphoblastic
ALL management is directed to control bone marrow and systemic disease (whole body). In addition, treatment should prevent leukemia cells from spreading to other sites, especially the central nervous system (CNS), for example. lumbar puncture every month. In general, ALL treatments are divided into several phases:
- Induction chemotherapy to bring bone marrow remission. For adults, standard induction plans include prednisone, vincristine, and anthracycline drugs; Other drug plans may include L-asparaginase or cyclophosphamide. For children with low-risk ALL, standard therapy usually consists of three drugs (prednisone, L-asparaginase, and vincristine) for the first month of treatment.
- consolidation therapy or intensification therapy to remove any remaining leukemia cells. There are many different approaches to consolidation, but it is usually a high-dose multi-drug treatment done over several months. Patients with low-to-average risk of ALL receive therapy with antimetabolite drugs such as methotrexate and 6-mercaptopurine (6-MP). High-risk patients receive higher doses of drugs from these drugs, plus additional drugs.
- CNS prophylaxis (preventive therapy) to stop the spread of cancer to the brain and nervous system in high-risk patients. Standard prophylaxis may include head and/or drug radiation delivered directly to the spine.
- Nursing care with chemotherapy drugs to prevent disease relapse after remission is achieved. Maintenance therapy usually involves lower doses of the drug, and may continue for up to three years.
- Alternatively, an allogeneic bone marrow transplant may be suitable for high-risk patients or relapse.
Chronic lymphocytosis
Decision to treat
Hematologists base CLL treatment on both stage and individual patient symptoms. A large group of CLL patients have low-grade disease, which does not benefit from treatment. Individuals with complications associated with CLL or more advanced disease often benefit from treatment. In general, the indications for treatment are:
- Loss of hemoglobin or platelet count
- Go to the next disease stage
- Pain, overgrowth associated with lymph nodes or spleen
- Increased lymphocyte production rate
Approach care
For most people with CLL, it can not be cured with current treatments, so treatment is directed to suppress the disease for years, rather than completely and permanently removing it. The main chemotherapy plan is a combination of chemotherapy with chlorambucil or cyclophosphamide, plus corticosteroids such as prednisone or prednisolone. The use of corticosteroids has the added benefit of suppressing some associated autoimmune diseases, such as immunohemolytic anemia or immune-mediated thrombocytopenia. In resistant cases, single-agent treatment with nucleoside drugs such as fludarabine, pentostatin, or cladribine may be successful. Younger and healthier patients may choose either an allogeneic or autologous bone marrow transplant in the hope of permanent cure.
Acute myelogenous
Many different anti-cancer drugs are effective for the treatment of AML. Treatment varies according to the age of the patient and corresponds to the specific subtype of AML. Overall, this strategy is to control bone marrow and systemic (body-wide) disease, while offering special care for the central nervous system (CNS), when involved.
In general, most oncologists rely on a combination of drugs for the initial phase of chemotherapy phases of induction. Such combination chemotherapy usually offers benefits from early remission and lower risk of disease resistance. Consolidation and care care is intended to prevent recurrence of the disease. Consolidated care often requires repeated induction chemotherapy or intensified chemotherapy with additional drugs. In contrast, treatment treatments involve lower drug doses than those provided during the induction phase.
Chronic myelogenous
There are many possible treatments for CML, but the standard of care for newly diagnosed patients is imatinib therapy (Gleevec). Compared to most anti-cancer drugs, these drugs have relatively few side effects and can be taken orally at home. With this drug, over 90% of patients will be able to keep the disease for at least five years, so CML becomes a chronic condition that can be treated.
In more advanced and uncontrolled circumstances, when the patient is unable to tolerate imatinib, or if the patient wishes to try permanent healing, an allogeneic bone marrow transplant can be performed. This procedure involves high-dose chemotherapy and radiation followed by bone marrow infusion from a compatible donor. About 30% of patients die from this procedure.
Hairy cell
Decision to treat
Patients with symptom-free hairless leukemia usually do not receive immediate treatment. Treatment is generally considered necessary when the patient shows signs and symptoms such as low blood cell count (eg, number of neutrophils fighting infections below 1.0Ã, K/ÂμL), frequent infections, unexplained bruises, anemia, or fatigue significant enough to disrupt the daily life of the patient.
Special treatment approach
Patients requiring treatment usually receive one week of cladribine, administered daily with intravenous infusion or simple injections under the skin, or six months of pentostatin, given every four weeks with intravenous infusion. In most cases, one treatment cycle will result in a prolonged remission.
Other treatments include rituximab infusion or self-injection with Interferon-alpha. In limited cases, patients may benefit from splenectomy (removal of the spleen). This treatment is usually not given as a first treatment because their success rate is lower than cladribine or pentostatin.
Prolymphocytic cell-T
Most patients with T-cell probolphocytic leukemia, rare and aggressive leukemia with a median survival of less than one year, require immediate care.
T-cell proukphocytic leukemia is difficult to treat, and does not respond to most of the available chemotherapy drugs. Many different treatments have been tried, with limited success in certain patients: purine analogues (pentostatin, fludarabine, cladribine), chlorambucil, and various forms of combination chemotherapy (cyclophosphamide, doxorubicin, vincristine, prednisone CHOP, cyclophosphamide, vincristine, prednisone [COP] vincristine, doxorubicin, prednisone, etoposide, cyclophosphamide, bleomycin VAPEC-B). Alemtuzumab (Campath), a monoclonal antibody that attacks white blood cells, has been used in treatment with greater success than the previous option.
Some patients who respond successfully to treatment also undergo stem cell transplantation to consolidate the response.
Juvenile myelomonocytic
Treatment for adult myelomonocytic leukemia may include splenectomy, chemotherapy, and bone marrow transplantation.
Prognosis
The success of treatment depends on the type of leukemia and the age of the person. Results have increased in developed countries. The average five-year survival rate is 57% in the United States. In children under 15 years, the five-year survival rate is greater than 60 to 85%, depending on the type of leukemia. In children with acute cancer-free acute leukemia after five years, cancer is unlikely to return.
The results depend on whether it is acute or chronic, certain abnormal white blood cell types, the presence and severity of anemia or thrombocytopenia, tissue abnormality rate, presence of metastases and lymph node and bone marrow infiltration, availability of therapy and skill of health care team. Treatment outcomes may be better when people are treated in larger centers with greater experience.
Epidemiology
In 2010, globally, about 281,500 people died of leukemia. In 2000, about 256,000 children and adults worldwide developed a form of leukemia, and 209,000 died of it. It represents about 3% of the nearly seven million cancer deaths that year, and about 0.35% of all deaths due to any cause. Of the sixteen separate sites that are compared with the body, leukemia is the 12th class of the most common neoplastic diseases, and the 11th most common cause of cancer-related deaths. Leukemia occurs more commonly in developed countries.
United States
About 245,000 people in the United States are affected by some forms of leukemia, including those who have achieved remission or healing. The rate from 1975 to 2011 has increased by 0.7% per year among children. Approximately 44,270 new leukemia cases were diagnosed in 2008 in the US. It represents 2.9% of all cancers (excluding simple basal cells and squamous cell skin cancer) in the United States, and 30.4% of all blood cancers.
Among children with some forms of cancer, about one-third have the type of leukemia, the most common acute lymphoblastic leukemia. This type of leukemia is the second most common form of cancer in infants (under 12 months of age) and the most common form of cancer in older children. Boys are somewhat more likely to develop leukemia than girls, and white American children are almost twice as likely to develop leukemia than American black children. Only about 3% of cancer diagnoses in adults for leukemia, but because cancer is much more common among adults, more than 90% of all leukemia is diagnosed in adults.
Race is a risk factor in the United States. Hispanics, especially those under 20, are at the highest risk for leukemia, while whites, Native Americans, Asians and Alaskan Natives are at higher risk than African Americans.
More men than women who were diagnosed with leukemia and died of the disease. About 30 percent more men than women have leukemia.
English
Overall, leukemia is the 11th most common cancer in the UK (about 8,600 people diagnosed with the disease in 2011), and it is the ninth most common cause of cancer deaths (about 4,800 people die in 2012).
History
Leukemia was first described by anatomist and surgeon Alfred-Armand-Louis-Marie Velpeau in 1827. A more complete explanation was given by pathologist Rudolf Virchow in 1845. About ten years after Virchow's discovery, the pathologist Franz Ernst Christian Neumann discovered that one leukemia patient died of a "dirty green-yellow" colored bone marrow as opposed to normal red. This finding allowed Neumann to conclude that bone marrow problems are responsible for abnormal blood of leukemia patients.
In 1900 leukemia was seen as a family of diseases compared to a single disease. In 1947, Boston pathologist Sidney Farber believed from earlier experiments that aminopterin, a folic acid that mimics, has the potential to cure leukemia in children. The majority of children with ALL tested showed signs of improvement in their bone marrow, but none were completely healed. This, however, led to further experiments.
In 1962, researcher Emil J. Freireich, Jr. and Emil Frei III uses a combination chemotherapy to try to cure leukemia. The test was successful with some patients who survived long after the test.
Etymology
Observing large numbers of white blood cells in blood samples from a patient, Virchow mentions the condition of LeukÃÆ'¤mie in German, which he forms from the two Greek words leukos (???? ??), meaning "white", and haima (????), which means "blood".
Society and culture
According to Susan Sontag, leukemia is often romantized in 20th century fiction, described as a clean illness that ends in joy, whose victims are just, innocent and gentle to die young or at the wrong time. Thus, it is the cultural successor of tuberculosis, which holds this cultural position until it is found to be a contagious disease. Novel romance 1970 Love Story is an example of romanticizing this leukemia.
In the United States, about $ 5.4 billion is spent on maintenance a year.
Direction of research
Significant studies of the causes, prevalence, diagnosis, treatment, and prognosis of leukemia are underway. Hundreds of clinical trials are being planned or performed at any given time. Studies may focus on effective ways of treatment, better ways to treat illness, improve patient quality of life, or proper care in forgiveness or after healing.
In general, there are two types of leukemia research: clinical or translation research and basic research. Clinical/translational studies focus on studying the disease in the prescribed manner and generally apply directly to the patient, such as testing a new drug in a patient. In contrast, basic science studies study distant disease processes, such as see if suspected carcinogens can cause leukemia changes in isolated cells in the laboratory or how DNA changes in leukemia cells as disease develops. Results from basic research studies are generally less immediate for patients with disease.
Treatment through gene therapy is currently being pursued. One such approach uses genetically modified T cells to attack cancer cells. In 2011, a year after treatment, two of the three patients with sophisticated chronic lymphocytic leukemia were reported to be cancer-free and by 2013, three out of five patients with acute lymphocytic leukemia reported remission for five months to two years.. Identifying stem cells that cause different types of leukemia is also being studied.
Pregnancy
Leukemia is rarely associated with pregnancy, affecting only about 1 in 10,000 pregnant women. How it works depends mainly on the type of leukemia. Almost all leukemia appearing in pregnant women is acute leukemia. Acute leukemia usually requires rapid and aggressive treatment, although there is a significant risk of loss of pregnancy and birth, especially if chemotherapy is given during the first trimester progressively progresses. Chronic myelogenous leukemia can be treated with relative safety at any time during pregnancy with interferon-alpha hormone. Treatment for chronic lymphocytic leukemia, which is rare in pregnant women, can often be delayed until after the end of pregnancy.
See also
- Acute erythroid leukemia
- Antileukemic drugs, drugs used to kill leukemia cells
- Haematological disease, a large class of blood-related disorders, including leukemia
- Cancer-related fatigue
References
External links
- Leukemia in Curlie (based on DMOZ)
- Leukemia Information from Cancer Research UK
Source of the article : Wikipedia
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