Leukemia is a term for cancers of the blood cells. Leukemia starts in blood-forming tissues such as the bone marrow. Your bone marrow makes the cells which will develop into white blood cells, red blood cells, and platelets. Each type of cell has a different job:

• White blood cells help your body fight infection
• Red blood cells deliver oxygen from your lungs to your tissues and organs
• Platelets help form clots to stop bleeding

When you have leukemia, your bone marrow makes large numbers of abnormal cells. This problem most often happens with white blood cells. These abnormal cells build up in your bone marrow and blood. They crowd out the healthy blood cells and make it hard for your cells and blood to do their work.

Acute lymphocytic leukemia is a type of acute leukemia. It's also called ALL and acute lymphoblastic leukemia. "Acute" means that it usually gets worse quickly if it's not treated. ALL is the most common type of cancer in children. It can also affect adults.

In ALL, the bone marrow makes too many lymphocytes, a type of white blood cell. These cells normally help your body fight infection. But in ALL, they are abnormal and cannot fight infection very well. They also crowd out the healthy cells, which can lead to infection, anemia, and easy bleeding. These abnormal cells can also spread to other parts of the body, including the brain and spinal cord.

ALL happens when there are changes in the genetic material (DNA) in bone marrow cells. The cause of these genetic changes is unknown. However, there are certain factors that raise your risk of ALL.

The factors that raise your risk of ALL include:

• Being male
• Being white
• Being over age 70
• Having had chemotherapy or radiation therapy
• Having been exposed to high levels of radiation
• Having certain genetic disorders, such as Down syndrome

The signs and symptoms of ALL include:

• Weakness or feeling tired
• Fever or night sweats
• Easy bruising or bleeding
• Petechiae, which are tiny red dots under the skin. They are caused by bleeding.
• Shortness of breath
• Weight loss or loss of appetite
• Pain in the bones or stomach
• Pain or feeling of fullness below the ribs
• Swollen lymph nodes - you may notice them as painless lumps in the neck, underarm, stomach, or groin
• Having had many infections

Your health care provider may use many tools to diagnose ALL and figure out which subtype you have:

• A physical exam
• A medical history
• Blood tests, such as
  • Complete blood count (CBC) with differential
  • Blood chemistry tests such as a basic metabolic panel (BMP), comprehensive metabolic panel (CMP), kidney function tests, liver function tests, and electrolyte panel
  • Blood smear
• Bone marrow tests. There are two main types - bone marrow aspiration and bone marrow biopsy. Both tests involve removing a sample of bone marrow and bone. The samples are sent to a lab for testing.
• Genetic tests to look for gene and chromosome changes

If you are diagnosed with ALL, you may have additional tests to see whether the cancer has spread. These include imaging tests and a lumbar puncture, which is a procedure to collect and test cerebrospinal fluid (CSF).

Treatments for ALL include:

• Chemotherapy
• Radiation therapy
• Chemotherapy with stem cell transplant
• Targeted therapy, which uses drugs or other substances that attack specific cancer cells with less harm to normal cells

Treatment is usually done in two phases:

• The goal of the first phase is to kill the leukemia cells in the blood and bone marrow. This treatment puts the leukemia into remission. Remission means that the signs and symptoms of cancer are reduced or have disappeared.
• The second phase is known as post-remission therapy. Its goal is to prevent a relapse (return) of the cancer. It involves killing any remaining leukemia cells that may not be active but could begin to regrow.

Treatment during both phases also usually includes central nervous system (CNS) prophylaxis therapy. This therapy helps prevent the spread of leukemia cells to the brain and spinal cord. It may be high dose chemotherapy or chemotherapy injected into the spinal cord. It also sometimes includes radiation therapy.

NIH: National Cancer Institute