Leukemia affects almost 29,000 Americans each year.
Because leukemia affectes about 2,000 children and 27,000 adults in the United States each year, according to Cancer Treatment Centers of America, the quest to isolate leukemia causes is important. While researchers have not pinpointed the main causes of leukemia, they have found evidence supporting environmental and genetic factors involved in the disease. These factors vary based on the type of leukemia and include mutated genes and exposure to toxic chemicals and radiation.
Because leukemia causes vary by the type of cancer, it can be helpful for a person to understand the different types. Doctors classify leukemia in one of two methods. The first is how quickly the disease progresses. This classification results in a diagnosis of acute or chronic leukemia. In acute leukemia, the cancer moves quickly, but in chronic leukemia, the cells mutate at a slower pace. The second classification depends on the type of cells affected by the leukemia. If the cancer affects lymphoid cells, doctors classify it as lymphocytic leukemia. In myelogenous leukemia, the cancer mutates myeloid cells. Using these classifications, doctors organize the disease into four main names:
Leukemia is the most frequently occurring kind of childhood cancer. According to Environmental Health Perspectives, ALL occurs approximately five times more frequently than AML in children under the age of 15 who have the disease. Researchers suspect in-utero genetic events as a part of the cause for ALL. Gene fusions with the MLL gene are common in cases of infant acute leukemia. The presence of some genetic polymorphisms that encode enzymes which encode carcinogens and drugs may predict the onset of the disease.
Other genes that may have an association with leukemia causes include an overactive TEL2 gene and a fusion of two genes that result in protein called MN1-TEL. Researchers at the St. Jude Childrens Research Hospital have found that an overactive TEL2 gene is present in 30 percent of children with ALL. According to this research, the cell must undergo two mutations in order to cause ALL. In regards to MN1-TEL protein, researchers at St. Jude believe it makes certain white blood cells mutate into leukemia cells. In order for the mutation to occur, the protein needs another leukemia trigger.
Along with certain genes, heredity can also contribute to leukemia causes. Doctors believe that inherited diseases, like Fanconi anemia and ataxia telangiectasia, increase the chances of developing leukemia. These diseases have an association with an atypical number of chromosomes or defective DNA. Individuals with a family history of hematopoietic malignancies may have a somewhat increased risk for developing leukemia. Further indicating a connection between heredity and leukemia is the increase in risk for a child to develop leukemia when he or she has a sibling with the disease.
In addition to genetic factors, researchers and doctors have found a connection between environmental causes, such as exposure to radiation and exposure to toxic chemicals, like hydrocarbons and pesticides. Ionizing radiation exposure may affect the infant before conception, during pregnancy or after the infant is born. Ionizing radiation is linked most often with AML. The risk of developing AML from ionizing radiation depends on the duration, the dose and the age of the person exposed to ionizing radiation. Usually exposure results from atomic bombs, close proximity to nuclear facilities or x-rays done on the lower abdomen.
Research indicates a connection between exposure to hydrocarbons and toxic chemicals and the development of leukemia. Researchers show a significant positive exposure-response relationship between benzene and AML. ALL also has a strong association with benzene found in paint.
Along with hydrocarbons, toxic chemicals like pesticides show an association with leukemia causes. As of 2008, researchers need to conduct more studies to determine the connection between pesticides and childhood cancers. Exposure from pesticides can occur from home lawn or garden products, contaminated food, parental occupation, local agricultural uses or professional exterminations.
Other toxic chemicals include exposure to alcohol, cigarettes or illicit drugs. Maternal alcohol consumption during pregnancy causes an increase in the risk of AML. Studies on the relationship between smoking and leukemia show mixed results, indicating a need for further study. As far as illicit drugs, the use of marijuana before and during pregnancy increases the risk of developing AML or ALL.