The Differences Between Acute and Chronic Leukemia

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Leukemia is cancer of the body’s white blood cells; it develops in the bone marrow and lymphatic system and then spills over into the blood stream. The four types of leukemia are divided into two categories: acute and chronic. Acute leukemia involves the immature cells, called stem cells, whereas chronic leukemia develops in mature cells. However, there is much more to understand about these two types of leukemia, including their subcategories.

Acute leukemias progress quickly because they affect stem cells, called blasts, which divide rapidly—both normal blood cells and cancerous ones. The problem is the abnormal cells invade the blood quickly because they don’t stop dividing when they should. Because they are so fast-growing, acute leukemias often spread to a person’s organs and central nervous system. Many people with acute forms of leukemia will experience symptoms of easy bleeding and bruising, fatigue, unintended weight loss, and frequent infections.

This is a serious form of cancer. Without treatment, the prognosis for acute leukemia is grim, with most people surviving only a few months. However, some types of acute leukemia can be cured with proper treatment.

There are two types of acute leukemia:

• Acute lymphocytic (also called lymphoblastic) leukemia (ALL): This type of cancer develops when abnormal immature lymphocytic white blood cells begin to divide out of control. Mature lymphocytes are responsible for making antibodies.

• Acute myelogenous (also called myeloid) leukemia (AML): This disease can begin with immature white blood cells other than those that become lymphocytes. It also develops in other types of immature blood cells—red blood cells and platelets. AML has several subtypes, categorized by the type and maturity of the cells in which the disease develops.

Women are more likely than men to develop ALL, especially beginning after age 45. Men are more likely to develop all other types of leukemias. Children are also more likely to develop ALL than AML. About 75% of all childhood leukemias are ALL, with the rest being AML.

Treatments can be effective for people with acute leukemia, particularly ALL. More than 80% of people have complete remission of the disease, and about 40% are cured. Types of treatment include:

• Chemotherapy
• Stem cell transplant, which replaces a person’s bone marrow with new marrow
• Radiation therapy, which uses X-rays to kill cancer cells, often used when the cancer has spread to the central nervous system
• Targeted drugs, which attack a specific aspect of cancer cells
• Clinical trials testing new treatments and procedures

In chronic leukemia, the abnormal cells are partly mature and often appear normal. When these cells develop into leukemia cells, they don’t fight off illness as well, and they survive longer than normal white blood cells, allowing them to build up in the blood.

These types of cancer progress more slowly than acute leukemias. People often exhibit no symptoms and can live many years after developing the disease. However, chronic leukemias don’t respond as well to treatment, making them more difficult to cure.

There are two types of chronic leukemia:

• Chronic lymphocytic leukemia (CLL): This disease develops from partly mature white blood cells called lymphocytes. It begins in the bone marrow but then moves into the blood. There are two types of CLL, one that grows slowly, and another that develops more quickly and is more serious.

• Chronic myelogenous leukemia (CML): This form of leukemia begins with a genetic change in non-lymphocytic white blood cells, red blood cells, and platelets. An abnormal gene then begins turning normal cells into CML cells. While this is a slow-growing type of leukemia, it can also turn into an acute, fast-growing leukemia.

Men develop chronic leukemias at a much higher rate than women, though CML is uncommon in both genders and all age groups. Chronic leukemias are rare in children.

Treatments include:

• Targeted drugs
• Biological therapy with monoclonal antibodies: man-made drugs that help the immune system kill cancer cells, used mostly with CLL
• Biological therapy with interferon: an injection of substances made in the immune system, used mostly with CML
• Chemotherapy
• Stem cell transplant
• Clinical trials testing new treatments and procedures

Understanding the differences between acute and chronic forms of leukemia is critical in forming a plan of action to deal with the disease. Talk with a doctor about your symptoms and the best treatment plan for your condition.