Leukemias are cancers that develop from blood cells. Though there are several different types of leukemia, they are generally classified as either “chronic” or “acute.” The main difference between these two categories is that chronic leukemias are slow-growing, and acute leukemias grow quickly. Because acute and chronic cancers progress at different speeds, they can cause different sets of symptoms and respond differently to treatments.

Normal Blood Cell Function

Understanding blood cells and how they develop can shed light on the difference between chronic and acute leukemias.

Your blood is made up of several different types of cells, including red blood cells, white blood cells, and platelets. Each of these cells plays a different role in keeping your body healthy.

• Red blood cells deliver oxygen to cells around the body and help get rid of waste products.
• White blood cells fight infection by attacking and removing foreign particles like germs.
• Platelets form blood clots and help prevent you from bleeding too much.

All of these blood cells develop from immature cells called hematopoietic stem cells (HSCs). HSCs live in the bone marrow, the soft tissue that fills the insides of bones. In order to make new blood cells, HSCs make copies of themselves. Some of the copies are slightly more mature cells called progenitor cells. The progenitor cells grow and divide in order to produce other cells that are even more mature. This process repeats until fully developed, mature blood cells are formed. HSCs make billions of new blood cells every day.

What Is Leukemia?

Cells contain genes, which act as instructions that determine the jobs that the cell performs within the body. When genes undergo certain changes, cancer can develop. These gene changes may make it more difficult for a cell to repair damage, or they may increase a cell’s growth. Some people are born with these cancerous gene changes, while others develop them later in life when cells become damaged.

Leukemia arises when a single blood cell develops certain cancer-causing gene changes. Leukemia usually begins in an immature stem or progenitor cell. If one of these cells becomes damaged, it may become cancerous and grow out of control. This can cause a few big problems:

• The cancer cells are abnormal and immature, and can’t carry out the functions of normal blood cells.
• The cancer cells multiply quickly and take over the bone marrow and the blood, crowding out the normal blood cells.
• The bone marrow will no longer make as many normal blood cells as it used to, leading to problems throughout the body.

Types of Leukemia

There are several types of leukemia. Experts classify leukemia as myeloid or lymphoid based on which cell type became cancerous. Myeloid cells make platelets, red blood cells, and some types of white blood cells, and lymphoid cells make other types of white blood cells called lymphocytes. Experts further classify these types of leukemia as either acute or chronic based on how fast they grow.

Acute Leukemia

Acute leukemias develop and get worse very quickly. Acute leukemia cells are very immature and can’t perform any of the tasks that blood cells need to do. If you have acute leukemia, you will likely start feeling sick within weeks of developing the disease. You will need to begin treatment right away.

Chronic Leukemia

Chronic leukemias grow more slowly. It may be several months or even years before you start experiencing symptoms. Chronic leukemia cells are more mature than acute leukemia cells, but they are still not yet fully developed. They may be able to carry out some of the tasks of normal blood cells, but they still don’t work properly.

Main Types of Leukemias

There are four main types of leukemia, based on the above classifications:

• Acute myeloid leukemia — This is the most common type of acute leukemia in adults.
• Acute lymphocytic leukemia — Leukemia in children is most often this type.
• Chronic myeloid leukemia — This form of leukemia is seen in adults more often than in children.
• Chronic lymphocytic leukemia — This is the most common type of chronic leukemia seen in adults.

Each of these four types of leukemia also consists of many subtypes. Other types of leukemia also exist, but they are often rare. Read more about the types of leukemia.

Symptoms in Acute vs. Chronic Leukemia

Because acute and chronic leukemias progress at different paces, they can look and feel different within the body.

Acute leukemia is more likely to cause severe symptoms that appear early on in the disease. Symptoms of acute leukemia may include:

• Tiredness
• Shortness of breath
• Pale skin
• Bruising or discolored spots under the skin
• Bleeding problems
• Unexpected weight loss
• Bone or joint pain
• Fever
• Frequent infections

Chronic leukemia symptoms are usually milder and may not appear until later stages of the disease. Symptoms of chronic leukemia include:

• Feelings of tiredness or weakness
• Swollen lymph nodes, which will appear as lumps in the armpits, neck, or groin
• Abdominal pain and bloating
• Feelings of fullness in the stomach
• Fever or night sweats

Most often, symptoms found in both acute and chronic leukemia are caused by other health conditions. However, if you are experiencing any of these symptoms, talk to your doctor.

Diagnosing Different Types of Blood Cancers

Children are more likely to be diagnosed with acute leukemia, while chronic leukemias are more commonly diagnosed in adults. Doctors can determine which cell type has become cancerous through different diagnostic tests, including a complete blood count, peripheral blood smear, flow cytometry, and genetic tests. Read more about tests used to diagnose leukemia.

Treating Acute vs. Chronic Leukemia

Acute leukemias progress quickly, but they are often easier to cure than chronic leukemias. Although treatments may not work as well for chronic leukemias, chronic cancers are slow-growing and slow to cause problems. People can often live a long time with chronic myeloid leukemia or chronic lymphocytic leukemia.

Many types of therapies may be used to treat leukemia. When recommending a treatment plan, your doctor will take many factors into consideration, including how old you are, other health problems you may have, whether your leukemia has spread, and your type of leukemia.

Leukemia treatments may include the following:

• Chemotherapy — Chemotherapy drugs, which can kill quickly growing cancer cells, may be given alone or in combination with other medications.
• Targeted therapy — Targeted therapies can recognize and attack specific molecules found only within leukemia cells.
• Immunotherapy — Immunotherapy treatments boost your own immune system and enable it to fight off leukemia.
• Stem cell transplant — During a stem cell transplant, your bone marrow cells are killed and then you receive new HSCs that can create new, noncancerous blood cells.
• Radiation therapy — Radiation treatment uses beams of energy, such as X-rays, to damage cancer cells.
• Clinical trials — During clinical trials, researchers examine whether cancer treatments are safe and effective. Ask your doctor whether clinical trials could be a good option for you, as they provide access to new treatments that aren’t yet a part of standard care.

Finding Support for Leukemia

Navigating a new diagnosis can be overwhelming, but having a supportive network of people who understand may help make it easier. MyLeukemiaTeam is the social network for people with leukemia and their loved ones. By joining, you gain a support group of over 7,500 people. Members understand what it’s like to live with leukemia and are ready with advice, support, and answers when you’re trying to learn more about this disease.

Have you or a loved one been recently diagnosed with acute or chronic leukemia? Comment with your experiences below, or post on MyLeukemiaTeam to start a conversation.