Leukemia: Symptoms, Signs, Causes, Types & Treatment (2024)

What is leukemia?

Leukemia is a cancer of the blood, characterized by the rapid growth of abnormal blood cells. This uncontrolled growth takes place in your bone marrow, where most of your body’s blood is made. Leukemia cells are usually immature (still developing) white blood cells. The term leukemia comes from the Greek words for “white” (leukos) and “blood” (haima).

Unlike other cancers, leukemia doesn’t generally form a mass (tumor) that shows up in imaging tests, such as X-rays or CT scans.

There are many types of leukemia. Some are more common in children, while others are more common in adults. Treatment depends on the type of leukemia and other factors.

How does leukemia develop?

Leukemia begins in bone marrow, the soft spongy tissue in the inner cavity of your bones, where your body’s blood cells are made. Blood cells go through multiple stages before reaching their fully mature forms. Mature, normal blood cells include:

• Red blood cells: Cells that carry oxygen and other vital materials to all tissues and organs in your body.
• White blood cells: Cells that fight infection.
• Platelets: Cells that help your blood clot.

These blood cells start as hematopoietic (hemo = blood, poiesis = make) stem cells. The stem cells develop into either myeloid (MAI-uh-loyd) cells or lymphoid (LIM-foyd) cells. If blood cells were to continue to develop normally, the mature forms of these cells are as follows:

• Myeloid cells develop into red blood cells, platelets and certain types of white blood cells (basophils, eosinophils and neutrophils).
• Lymphoid cells develop into certain white blood cells (lymphocytes and natural killer cells).

However, if you have leukemia, one of the developing blood cells begins to multiply out of control. These abnormal cells — called leukemia cells — begin to take over the space inside of your bone marrow. They crowd out the cells trying to develop into healthy red blood cells, white blood cells and platelets.

How does leukemia affect my body?

Having too many leukemia cells and too few normal cells is harmful for several reasons:

• Leukemia cells serve no purpose in keeping you healthy.
• Normal blood cells have very little space and support to mature and multiply inside of your bone marrow because the leukemia cells overtake them.
• Fewer red blood cells, healthy white blood cells and platelets are made and released into your blood. As a result, your body’s organs and tissues won’t get the oxygen needed to work properly. Also, your body won’t be able to fight infections or form blood clots when needed.

What are the different types of leukemia?

There are four main types of leukemia and several subtypes. Healthcare providers classify leukemia based on how fast the disease worsens and whether leukemia cells arise from myeloid cells or lymphoid cells.

Classifications of leukemia

Healthcare providers classify leukemia based on how quickly it progresses and the type of blood cell involved.

By speed of disease progression

• Acute leukemia. The leukemia cells divide rapidly and the disease progresses quickly. If you have acute leukemia, you’ll feel sick within weeks of the leukemia cells forming. Acute leukemia is life-threatening and requires immediate initiation of therapy. Acute leukemia is the most common cancer in children.
• Chronic leukemia. Often, these leukemia cells behave as both immature and mature blood cells. Some cells develop to the point where they function as the cells they were meant to become — but not to the extent their normal counterparts do. The disease typically worsens slowly compared to acute leukemia. If you have chronic leukemia, you may not have noticeable symptoms for years. Chronic leukemia is more common in adults than in children.

By cell type

• Myelogenous (mai-uh-lOW-juh-nuhs) or myeloid leukemia develops from myeloid cells. Normal myeloid cells develop into red blood cells, white blood cells and platelets.
• Lymphocytic leukemia develops from lymphoid cells. Normal lymphoid cells develop into white blood cells that are an important part of your body’s immune system.

Types of leukemia

There are four main types of leukemia:

• Acute lymphocytic leukemia (ALL) is the most common type of leukemia in children, teens and young adults up to age 39. ALL can affect adults of any age.
• Acute myelogenous leukemia (AML)is the most common type of acute leukemia in adults. It’s more common in older adults (those over 65). AML also occurs in children.
• Chronic lymphocytic leukemia (CLL) is the most common chronic leukemia in adults (most common in people over 65). Symptoms may not appear for several years with CLL.
• Chronic myelogenous leukemia (CML) is more common in older adults (most common in people over 65) but can affect adults of any age. It rarely occurs in children. Symptoms may not appear for several years with CML.

How common is leukemia?

Leukemia is the 10th most common cancer in the U.S., accounting for 3.2% of all new cancer cases. Leukemia can affect anyone, but it’s more common among people who are:

• Ages 65 to 74.
• Assigned male at birth (AMAB).
• Caucasian/white.

Many people think of leukemia as a pediatric cancer, but some forms develop more often in adults. Although leukemia is rare in children, it’s the most common form of cancer affecting children and teens.