Leukemia

Leukemia is the most common type of blood cancer. Most people have heard of leukemia and have an idea about how scary the diagnosis might be. It may surprise you to know that some leukemias are not as scary as others. Leukemia is a big subject, so we will talk about it this week and next. Let's get started.

What is leukemia?

Leukemia is a type of blood cancer that starts in white blood cells. The name leukemia comes from the word leukocyte, which is another name for white blood cells (WBCs). Leukocytes grow in the bone marrow from stem cells. Stem cells in the bone marrow can develop into red blood cells, white blood cells (leukocytes), or platelets. They each have a specific function within the blood. WBCs help to fight infections. Once they are formed from the stem cells, WBCs don't usually divide and make more cells on their own. They wait in the bone marrow until they are needed, then are released into the circulation. Most WBCs live for a short time, hours to days.

Leukemia happens when the genetic material inside the cell, called DNA, is damaged or altered in some way. The damaged DNA tells the cells to continue growing and dividing and keeps them from maturing properly. As they multiply, they overwhelm the bone marrow. This slows down and eventually stops the production of normal WBCs, red blood cells, and platelets.

How are leukemias classified?

Leukemias are put into categories based on two things:

How fast the condition is developing:

• Acute leukemia - In acute leukemia, the abnormal WBCs are very immature. They can't carry out any normal function, and they multiply quite rapidly. The disease progresses quickly. These leukemias require aggressive and timely treatment.
• Chronic leukemia - These abnormal cells are more mature. They can perform some of their functions for a period of time. They multiply and accumulate more slowly. Some forms of chronic leukemia can go unnoticed or undiagnosed for years. They are often discovered by accident when a patient comes in for another issue that requires blood work, sometimes a wellness exam.

Which type of white blood cell is involved:

• Lymphocytes - Lymphocytic leukemia affects the lymphocytes, which include T cells and B cells, and natural killer cells. Each of these cell types has a specialized role in the immune system. Some produce antibodies. Some directly fight infections (or direct other cells to fight). They are the best fighters against viruses.
• Myeloid cells - Myelogenous leukemia affects the cells that give rise to white blood cells called granulocytes and monocytes. These make up most of the white blood cells circulating in the blood. They carry enzymes to fight infections or actually swallow up bacteria and fungi.

What are the different types of leukemia?

The major types of leukemia are:

• Acute lymphocytic leukemia (ALL) - The most common type of leukemia in young children but can also occur in adults.
• Acute myelogenous leukemia (AML) - A common type of leukemia, which occurs in children and adults. AML is the most common type of acute leukemia in adults.
• Chronic lymphocytic leukemia (CLL) - The most common chronic adult leukemia. Someone with CLL may feel well for years without needing treatment.
• Chronic myelogenous leukemia (CML) - Mainly affects adults. A person with CML may have few or no symptoms for months or years before entering a phase in which the leukemia cells grow more quickly.
• Other types - Other, rarer types of leukemia exist, including hairy cell leukemia, myelodysplastic syndromes and myeloproliferative disorders.

Next week, we will continue our discussion of leukemia.

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Dr. Anita Bennett MD - Health Tip Content Editor