What Are the 4 Types of Leukemia? Causes & Symptoms

Leukemia is classified broadly into two types depending on the rate at which it progresses: acute and chronic. 

• Acute leukemia: Abnormal blood cells multiply at a faster rate and give rise to symptoms quickly. 
• Chronic leukemia: Abnormal blood cells are produced more slowly and multiply gradually before speeding up and forming cancerous cells.

Leukemia is also classified based on the type of cells that become cancerous: lymphocytic leukemia and myeloid (myelogenous) leukemia. 

• Lymphocytic leukemia: Cancer affects the lymphoid cells (lymphocytes), which are a part of the immune system. 
• Myeloid leukemia: Affects the myeloid cells (granulocytes and monocytes) of the bone marrow. Myeloid cells help produce red blood cells (RBCs), white blood cells (WBCs), and platelets.

Acute lymphocytic leukemia (ALL)

ALL is the most common form of leukemia in children.

It is still unknown what causes the rapid formation of cancerous cells in ALL. However, certain factors such as advanced age (over 70) and a history of cancer treatment may increase the risk.

Symptoms develop quickly and may include:

• Fatigue
• Shortness of breath
• Fever
• Easy bruising or bleeding
• Bleeding that cannot be controlled easily

Chronic lymphocytic leukemia (CLL)

CLL is the most common type of leukemia in adults. According to the American Cancer Society, approximately 1 in every 175 people may develop CLL.

Symptoms develop slowly and may include:

• Swelling in the lymph nodes (neck, underarm, abdomen, or groin)
• Fatigue
• Fever of unknown cause
• Recurrent infections
• Weight loss

Acute myeloid leukemia (AML)

AML is the fastest growing type of leukemia in adults. Smoking and previous exposure to cancer treatments increase the risk of developing AML.

Symptoms develop quickly and may include:

• Fever
• Fatigue
• Night sweats
• Easy bruising
• Excessive bleeding
• Weight loss

Chronic myeloid leukemia (CML)

According to the American Cancer Society, CML accounts for about 15% of leukemias.

Symptoms develop slowly and may include:

• Fatigue
• Fever
• Weight loss
• Enlarged spleen

Chronic leukemia is most often discovered during routine blood tests even before symptoms develop. Blood tests may show elevated levels of red blood cells and white blood cells and in some cases, leukemia cells may be detected.

Your doctor to check see if a person has developed signs of leukemia such as:

• Pale skin
• Enlargement of the liver and spleen
• Swollen lymph nodes

In order to confirm a diagnosis of leukemia, a bone marrow test or biopsy may be ordered. The test involves surgically removing a sample of bone marrow from the hipbone. The sample is then sent to a lab for analysis under a microscope.

Treatment for leukemia varies greatly depending on various factors that include:

• Type of leukemia
• Age
• Overall health
• Whether it has spread to other organs

One or a combination of the following treatments may be used:

• Chemotherapy: Chemotherapy involves administering pills or injections to kill cancerous cells.
• Radiation therapy: Radiation therapy involves targeting high-energy X-ray waves on a single part of the body or all over the body to kill cancerous cells. This kind of therapy may be administered before a bone transplant procedure.
• Targeted therapy: Targeted drug therapy involves targeting the processes that are involved in the formation of cancerous cells and killing them. Before initiating therapy, leukemia cells will be tested to see whether targeted therapy may be helpful.
• Bone marrow transplant: Also known as a stem cell transplant and hematopoietic stem cell transplantation, a bone marrow transplant is a surgical procedure that involves transplanting cells from either the patient’s stem cells or a donor's bone marrow into the patient’s bone marrow. A bone marrow transplant can help replace damaged bone marrow cells and promotes the formation of healthy blood cells. In some cases, a bone marrow transplant may help remove abnormal leukemia cells. Typically, chemotherapy or radiation therapy is administered weeks before a bone marrow transplant.
• Immunotherapy: Immunotherapy involves the use of medications that train the immune system to fight cancer.
• Chimeric antigen receptor (CAR) T-cell therapy: This therapy involves taking germ-fighting T-cells, engineering them to fight cancer, and putting them back into the body.
• Clinical trials: Clinical trials are done on patients to research better treatment options for their particular condition. Patients can consider participating in these trials after discussing the benefits and possible risks with their doctor.