Updated

Leukemia is a cancer of white blood cells that begins to grow uncontrollably in the bone marrow. It spreads throughout the body by infiltrating the bloodstream. Multiple types of leukemia exist. The National Cancer Institute estimated that 47,150 people will be newly diagnosed, and 23,540 people will die from leukemia in 2012.

Types of leukemia
Leukemia can be either acute (progresses slower) or chronic (requires immediate care). It can also be lymphocytic or myelogenous.

There are four common types of leukemia. Acute myeloid leukemia (AML) is most common in children. Acute lymphoblastic leukemia (ALL), chronic myeloid leukemia (CML) and chronic lymphocytic leukemia (CLL) are more common in adults, with the CLL the most frequent.

Doctor Peter Emanuel, chair of the Winthrop P. Rockefeller Cancer Institute, said, "We distinguish which type of leukemia a patient has first by examining their marrow cells under a microscope, and then by genetic and other laboratory testing."

Causes
As with other cancers, the exact cause is unknown but seem to stem from both genetics and environmental factors. White blood cells fight infection and typical turnover in an advantageous fashion. When a person has leukemia, his or her bone marrow produces an overabundance of white blood cells, which function haphazardly. Scientists postulate that this hyper-division and multiplication occurs when blood cells acquire certain DNA mutations. The congestion of mutated blood cells prevents the further creation of healthy blood cells, leading to leukemia's symptoms.

Symptoms
Although this can vary, different types of leukemia generally exhibit the same symptoms. Common signs include night sweats that cause an individual to change their pajamas or bed sheets, unintentional weight loss, loss of appetite, fevers, chills, fatigue and malaise, explained Edward A. Faber Jr., assistant professor of internal medicine at the University of Nebraska.

Diagnosis
Blood tests are central to diagnosing leukemia. The Leukemia & Lymphoma Society explained that a doctor will administer a complete blood count, which will assess all of the red cells, white cells and platelets. People with leukemia will have a high concentration of white blood cells and few red cells or platelets.  Other testings procedures include physical exams (with attention on lymph nodes, liver and spleen) and bone marrow tests, wherein bone marrow is removed from the hipbone and examined for leukemia cells at a laboratory.

It is critical that a person recently diagnosed with leukemia visit a hematologist at once. "It's especially critical," said Emanuel, "if they have been diagnosed with ALL or AML, as in most cases patients with acute leukemia need to be hospitalized immediately and then treated with chemotherapy."

Treatment
Common treatments for leukemia are chemotherapy, biological therapy, targeted therapy, radiation therapy and stem cell transplants. Chemotherapy is the primary form of treatment for leukemia. Whether taken by pill or injection, chemotherapy drugs kill cancerous cells. Biological therapy mobilizes your own natural defenses against the cancer with special medicines. Targeted therapy attempts to disrupt certain weak points of cancerous cells. Radiation therapy eliminates cancer cells with high-powered X-rays. With a stem cell transplant, doctors can replenish the patients' normal, functioning and healthy blood cells. This boosts the immune system and renders the cancerous blood cells vulnerable.

Amanda Termuhlen, medical director of the Jonathan Jaques Children's Cancer Center, said that treatments are available for leukemia through a pediatric oncologist or medical oncologist.

For more information visit the Leukemia Research Foundation, the Leukemia & Lymphoma Society and the Children's Leukemia Research Association.