Acute Lymphocytic Leukemia (ALL): Introduction 

What is cancer?

Cancer is when cells in the body change and grow out of control. Your body is made up of tiny building blocks called cells. Normal cells grow when your body needs them, and die when your body does not need them any longer. Cancer is made up of abnormal cells that grow even though your body doesn’t need them. In most types of cancer, the abnormal cells grow to form a lump or mass called a tumor.

What is leukemia?

Leukemia is different from most other types of cancer. Leukemia is cancer that starts in the bone marrow, which is where new blood cells are made. The bone marrow is a thick, sponge-like tissue in the center of certain bones.

Leukemia cells are early or premature forms of blood cells, most often white blood cells. When a person has leukemia, the body makes too many abnormal blood cells. These cells don't work the way they should and don't mature into functional cells. Leukemia cells do not usually form tumors, but they can travel with the blood all over the body. That means leukemia can affect organs all over the body.               

Two types of white blood cells can turn into leukemia: 

• Lymphoid cells (lymphocytes). This is called lymphocytic or lymphoblastic leukemia.

• Myeloid cells (myelocytes).This is called myeloid or myelogenous leukemia.

Leukemia can also be either acute or chronic. Acute leukemia tends to grow very quickly and needs to be treated right away. Chronic leukemia often grows more slowly.

What is acute lymphocytic leukemia (ALL)?

Acute lymphocytic leukemia (ALL) is a type of leukemia that starts in very early or premature forms of white blood cells called lymphocytes. These immature cells are called lymphoblasts, or just blasts. The condition is also known as acute lymphoblastic leukemia. As the blasts grow, they can crowd out the normal cells in the bone marrow. This can lead to not enough of different types of blood cells. 

People with ALL have too many lymphocytes in their blood, but these cells are not normal and don't help fight infection. In fact, people with ALL are more likely to get infections. They can also have not enough red blood cells (anemia), which can cause fatigue. And they can have not enough platelets, which can lead to excess bleeding or bruising. 

ALL is a type of acute leukemia. This means it tends to grow quickly and needs to be treated right away.

Subtypes of ALL

ALL also comes in different subtypes. These are based on what type of lymphocytes the leukemia starts in, and how mature the cells are. Which subtype of ALL you have can affect both your treatment and prognosis (outlook). Ask your healthcare provider about your subtype of ALL and what it means in your case. The subtypes include:

B-cell ALL

This subtype of ALL starts in B lymphocytes (B cells). It can be one of the below:      

• Early Pre-B ALL (may be called pro-B ALL)

• Common ALL

• Pre-B ALL

• Mature B-cell ALL (also known as Burkitt leukemia)

T-cell ALL

This subtype of ALL starts in T lymphocytes (T cells). It can be one of the below:

• Pre-T ALL

• Mature T-cell ALL

Another aspect of typing that's done for ALL is looking for a certain genetic change called the Philadelphia chromosome. This change is found only in leukemia cells. It's a key part of deciding on the best treatment plan. 

Talk with your healthcare provider

If you have questions about your ALL, talk with your healthcare provider. Your healthcare provider can help you understand more about this type of leukemia.