Leukemia is a type of cancer that affects the white blood cells in the body.  White blood cells, which are produced in the spongy, inner section of bones called marrow, help the body to fight infections. When a person has leukemia, his or her body doesn’t produce these cells normally. The abnormal white blood cells become leukemia cells. Leukemia cells eventually hinder the other cells in the blood – the over production of leukemia cells crowds out the red blood cells, which carry oxygen throughout the body and platelets, which help blood clots to form. 

Luekemia is often described as chronic or acute. Chronic means that the disease worsens slowly.  Acute means that the disease progresses rapidly.  Generally, people with chronic leukemia are adults. Acute leukemia can affect both adults and children. 

Leukemia is often categorized as either lymphocytic (lymphoblastic) or myeloid (meylogeneous).  In lymphocytic leukemia, a type of white blood cells called the lymphocytes, are affected. In myeloid leukemia, the bone marrow, which is where the leukemia cells are produced, is affected. 

These are the four major types of leukemia:

1. Chronic Lymphocytic Leukemia (CLL)

Usually occurs in people over 55. There are about 7,000 cases of CLL each year.

2. Acute Lymphocytic Leukemia (ALL)

The most common leukemia in young children, but can also affect adults. There are about 3,800 yearly cases of ALL.

3. Chronic Myeloid Leukemia (CML)

Usually affects adults. There are about 4,400 cases of CML a year.

4. Acute Myeloid leukemia (AML)

Affects both children and adults, with 10,600 new cases annually.

Hairy Cell Leukemia (HCL) is a rare form of cancer that creates cells with small surface projections, giving them a “hairy” appearance.  HCL makes up about 2% of leukemia cases. 

Risk Factors
It’s impossible to say why some people develop leukemia and others do not.  However, there are some risk factors that have been linked to the occurrence of the disease.  But just because a person has known-risk factors does not mean that he or she will develop leukemia. Conversely, some patients develop the disease without experiencing any of the risk factors. 

Chemical Exposure

Some chemicals are thought to increase a person’s risk of developing leukemia. Two of the chemicals that are most associated with leukemia are benzene and formaldehyde, which are commonly used in the chemical industry. Benzene, in addition to being found in chemical professions, is also present in tobacco smoke.

Radiation Exposure

to high levels of radiation, such as the amount of radiation released by atomic or hydrogen bombs and nuclear power plant explosions, greatly increases a person’s risk of leukemia. Radiation is also used medically, which means that a person undergoing intense radiation therapy runs the risk of developing leukemia. However, medical radiation is administered under very controlled conditions. Additionally, radiation used in diagnostic medicine, such as x-rays, has not been linked with cancer.

Chemotherapy

Chemotherapy is a cancer treatment that involves the ingestion of cancer-fighting drugs. Sometimes, patients who receive chemotherapy develop leukemia after many years, especially if the drug they are using contains alkylating agents.

Genetic diseases

Every person is born with 23 pairs of chromosomes, which are like a genetic map to the body. Sometimes, people are born with chromosomal abnormalities, which lead to genetic diseases – such as Down syndrome. It has been shown that those with genetic diseases are at a higher risk of developing leukemia.

Other potential risks include the Human T-Cell Leukemia Virus-I (HTLV-I) and myelodysplastic syndrome. HTLV-I causes a rare type of leukemia called T-cell leukemia. Although it is a virus, there is no evidence that HTLV-I is contagious. Myelodysplastic syndrome is a type of blood disease that leads to the development of AML. Both myelodysplastic syndrome and HTLV-I are quite rare.