Leukemia Quiz: Test Your Medical IQ

Leukemia is a cancer that begins in the bone marrow. Bone marrow is the soft inner part of some of your bones. In most cases, the cancer moves from the marrow into the blood cells. It can then spread to other parts of the body, such as organs and tissues. Leukemia itself develops as a result of the overgrowth of the white blood cells produced in the bone marrow.

While no one knows exactly what causes leukemia, some factors are known to increase the risk of certain leukemias. People are more likely to get leukemia if they:

- Had certain types of chemotherapy
- Were exposed to high amounts of radiation
- Were exposed to chemicals such as benzene
- Have genetic problems such as Down syndrome

Keep in mind that these are only risk factors. Most people with these risk factors do not develop leukemia, and most people who develop leukemia were not at risk due to these factors.

As seen in leukemia, bone marrow makes excessive numbers of abnormal white blood cells. Normal white blood cells fight infection and are involved in many aspects of the immune system. Leukemia cells are abnormal white blood cells that do not fight infection nor do other functions efficiently, and they grow faster and over a longer period of time than normal blood cells. Leukemia cells can "crowd out" or outnumber other cells, meaning that leukemia cells that do not function normally replace normal functioning white blood cells. Leukemia cells also compete with normal red blood cells and other blood components for space within the blood.

There are four main types of leukemia, which may either be acute (worsen suddenly) or chronic (worsen over time). Leukemia is a blood cancer that affects white blood cells called lymphocytes and myelocytes. With this is mind, the four main types of leukemia are:

- Acute lymphoblastic leukemia (ALL)
- Acute myelogenous leukemia (AML)
- Chronic lymphocytic leukemia (CLL)
- Chronic myelogenous leukemia (CML)

Other, more rare types of leukemia are:
- Juvenile myelomonocytic leukemia (JMML)
- Hairy cell leukemia

Leukemia, acute lymphoblastic leukemia (ALL) specifically, accounts for about 1 out of 3 cases of childhood cancer. It is the most common cancer in children and adolescents.

It goes without saying that the main goal of leukemia treatment is to destroy leukemia cells so that normal cells can form and function inside the bone marrow. According to the American Cancer Society's Survival Rates for Acute Childhood Leukemias, children are considered cured of leukemia when they are free of the disease for five years.

Stem cell transplantation is the newest treatment for leukemia. Because cells are microscopic structures that serve as the building blocks for life, stem cells are uniquely important because they can change into a wide variety of normal cells.

With respect to leukemia treatment, stem cell transplantation involves the replacement of damaged bone marrow cells (leukemia cells) with healthy cells (stem cells). With this kind of treatment, stem cells then become red blood cells, white blood cells, and blood platelets.

This is especially important because leukemia damages white blood cells and "crowds out" or replaces other blood cells and platelets.

Recall that there are four main types of leukemia. Aside from ALL, which is most commonly seen in children, the other three main types -- AML, CLL and CML -- are most commonly seen in men.