Leukemia

The Leukemia & Lymphoma Society (LLS) is a global leader in the fight against blood cancer. The LLS mission: Cure leukemia, lymphoma, Hodgkin disease and myeloma, and improve the quality of life of patients and their families. LLS funds lifesaving blood cancer research around the world, provides free information and support services, and is the voice for all blood cancer patients seeking access to quality, affordable, coordinated care.

Leukemia (also spelled leukaemia and pronounced /lukimi/[1] loo-KEE-mee-) is a group of blood cancers that usually begin in the bone marrow and result in high numbers of abnormal blood cells.[9] These blood cells are not fully developed and are called blasts or leukemia cells.[2] Symptoms may include bleeding and bruising, bone pain, fatigue, fever, and an increased risk of infections.[2] These symptoms occur due to a lack of normal blood cells.[2] Diagnosis is typically made by blood tests or bone marrow biopsy.[2]

Leukemia

Download Zip 🔥 https://cinurl.com/2y67o5 🔥

Treatment may involve some combination of chemotherapy, radiation therapy, targeted therapy, and bone marrow transplant, in addition to supportive care and palliative care as needed.[3][6] Certain types of leukemia may be managed with watchful waiting.[3] The success of treatment depends on the type of leukemia and the age of the person. Outcomes have improved in the developed world.[10] Five-year survival rate is 65% in the United States.[4] In children under 15 in first-world countries, the five-year survival rate is greater than 60% or even 90%, depending on the type of leukemia.[13] In children with acute leukemia who are cancer-free after five years, the cancer is unlikely to return.[13]

In 2015, leukemia was present in 2.3 million people worldwide and caused 353,500 deaths.[7][8] In 2012, it had newly developed in 352,000 people.[10] It is the most common type of cancer in children, with three-quarters of leukemia cases in children being the acute lymphoblastic type.[3] However, over 90% of all leukemias are diagnosed in adults, with CLL and AML being most common in adults.[3][14] It occurs more commonly in the developed world.[10]

Additionally, the diseases are subdivided according to which kind of blood cell is affected. This divides leukemias into lymphoblastic or lymphocytic leukemias and myeloid or myelogenous leukemias:[15]

Damage to the bone marrow, by way of displacing the normal bone marrow cells with higher numbers of immature white blood cells, results in a lack of blood platelets, which are important in the blood clotting process. This means people with leukemia may easily become bruised, bleed excessively, or develop pinprick bleeds (petechiae).[35]

White blood cells, which are involved in fighting pathogens, may be suppressed or dysfunctional. This could cause the person's immune system to be unable to fight off a simple infection or to start attacking other body cells. Because leukemia prevents the immune system from working normally, some people experience frequent infection, ranging from infected tonsils, sores in the mouth, or diarrhea to life-threatening pneumonia or opportunistic infections.[36]

If the leukemic cells invade the central nervous system, then neurological symptoms (notably headaches) can occur. Uncommon neurological symptoms like migraines, seizures, or coma can occur as a result of brain stem pressure. All symptoms associated with leukemia can be attributed to other diseases. Consequently, leukemia is always diagnosed through medical tests.

The word leukemia, which means 'white blood', is derived from the characteristic high white blood cell count that presents in most affected people before treatment. The high number of white blood cells is apparent when a blood sample is viewed under a microscope, with the extra white blood cells frequently being immature or dysfunctional. The excessive number of cells can also interfere with the level of other cells, causing further harmful imbalance in the blood count.[39]

Some people diagnosed with leukemia do not have high white blood cell counts visible during a regular blood count. This less-common condition is called aleukemia. The bone marrow still contains cancerous white blood cells that disrupt the normal production of blood cells, but they remain in the marrow instead of entering the bloodstream, where they would be visible in a blood test. For a person with aleukemia, the white blood cell counts in the bloodstream can be normal or low. Aleukemia can occur in any of the four major types of leukemia, and is particularly common in hairy cell leukemia.[40]

Studies in 2009 and 2010 have shown a positive correlation between exposure to formaldehyde and the development of leukemia, particularly myeloid leukemia.[41][42] The different leukemias likely have different causes.[43]

Leukemia, like other cancers, results from mutations in the DNA. Certain mutations can trigger leukemia by activating oncogenes or deactivating tumor suppressor genes, and thereby disrupting the regulation of cell death, differentiation or division. These mutations may occur spontaneously or as a result of exposure to radiation or carcinogenic substances.[44]

Among adults, the known causes are natural and artificial ionizing radiation and petrochemicals, notably benzene and alkylating chemotherapy agents for previous malignancies.[45][46][47] Use of tobacco is associated with a small increase in the risk of developing acute myeloid leukemia in adults.[45] Cohort and case-control studies have linked exposure to some petrochemicals and hair dyes to the development of some forms of leukemia. Diet has very limited or no effect, although eating more vegetables may confer a small protective benefit.[48]

A few cases of maternal-fetal transmission (a baby acquires leukemia because its mother had leukemia during the pregnancy) have been reported.[45] Children born to mothers who use fertility drugs to induce ovulation are more than twice as likely to develop leukemia during their childhoods than other children.[50]

In a recent systematic review and meta-analysis of any type of leukemia in neonates using phototherapy, typically to treat neonatal jaundice, a statistically significant association was detected between using phototherapy and myeloid leukemia. However, it is still questionable whether phototherapy is genuinely the cause of cancer or simply a result of the same underlying factors that gave rise to cancer. [51]

Some people have a genetic predisposition towards developing leukemia. This predisposition is demonstrated by family histories and twin studies.[45] The affected people may have a single gene or multiple genes in common. In some cases, families tend to develop the same kinds of leukemia as other members; in other families, affected people may develop different forms of leukemia or related blood cancers.[45]

In addition to these genetic issues, people with chromosomal abnormalities or certain other genetic conditions have a greater risk of leukemia.[46] For example, people with Down syndrome have a significantly increased risk of developing forms of acute leukemia (especially acute myeloid leukemia), and Fanconi anemia is a risk factor for developing acute myeloid leukemia.[45] Mutation in SPRED1 gene has been associated with a predisposition to childhood leukemia.[53]

Chronic myelogenous leukemia is associated with a genetic abnormality called the Philadelphia translocation; 95% of people with CML carry the Philadelphia mutation, although this is not exclusive to CML and can be observed in people with other types of leukemia.[54][55][56][57]

Whether or not non-ionizing radiation causes leukemia has been studied for several decades. The International Agency for Research on Cancer expert working group undertook a detailed review of all data on static and extremely low frequency electromagnetic energy, which occurs naturally and in association with the generation, transmission, and use of electrical power.[58] They concluded that there is limited evidence that high levels of ELF magnetic (but not electric) fields might cause some cases of childhood leukemia.[58] No evidence for a relationship to leukemia or another form of malignancy in adults has been demonstrated.[58] Since exposure to such levels of ELFs is relatively uncommon, the World Health Organization concludes that ELF exposure, if later proven to be causative, would account for just 100 to 2400 cases worldwide each year, representing 0.2 to 4.9% of the total incidence of childhood leukemia for that year (about 0.03 to 0.9% of all leukemias).[59]

Diagnosis is usually based on repeated complete blood counts and a bone marrow examination following observations of the symptoms. Sometimes, blood tests may not show that a person has leukemia, especially in the early stages of the disease or during remission. A lymph node biopsy can be performed to diagnose certain types of leukemia in certain situations.[60]

Following diagnosis, blood chemistry tests can be used to determine the degree of liver and kidney damage or the effects of chemotherapy on the person. When concerns arise about other damages due to leukemia, doctors may use an X-ray, MRI, or ultrasound. These can potentially show leukemia's effects on such body parts as bones (X-ray), the brain (MRI), or the kidneys, spleen, and liver (ultrasound). CT scans can be used to check lymph nodes in the chest, though this is uncommon.[61]

Despite the use of these methods to diagnose whether or not a person has leukemia, many people have not been diagnosed because many of the symptoms are vague, non-specific, and can refer to other diseases. For this reason, the American Cancer Society estimates that at least one-fifth of the people with leukemia have not yet been diagnosed.[40]

Most forms of leukemia are treated with pharmaceutical medication, typically combined into a multi-drug chemotherapy regimen. Some are also treated with radiation therapy. In some cases, a bone marrow transplant is effective. 17dc91bb1f