What is Leukemia?

Leukemia is a cancer of the blood and bone marrow in which abnormal blood cells multiple uncontrollably and spread through the bloodstream. Leukemia begins in the bone marrow where blood cells are made. Instead of producing all types of needed blood cells — red blood cells, white blood cells and platelets — the bone marrow will begin producing abnormal blood cells that rapidly reproduce and overtake the marrow and the bloodstream.

Multiple types of leukemia exist, some more common in children and others predominately found in adults. Leukemia can also be fast and proliferative (acute) or slow growing (chronic), typically based on which type of cells are first impacted.

What Are the Types of Leukemia?

The main types of leukemia are classified by how quickly it grows, and the type of white blood cells affected.

The first designation classifies leukemia as either acute (fast growing) or chronic (slow growing). Acute leukemia is caused by rapid multiplication of immature blood cells. In chronic leukemia, it is the more mature blood cells which slowly multiply—some forms of chronic leukemia cause reduced production of blood cells—and may not show symptoms or signs of leukemia for some time.

Leukemia may impact either white cells called lymphoid cells or those called myeloid cells. In lymphocytic leukemia, it is the lymphoid cells, part of lymphatic tissue and the immune system, that become malignant (cancerous). Myelogenous leukemia affects the myeloid cells, which in the normal setting are destined to become red blood cells, white blood cells and platelet-producing cells.

The most common types of leukemia are:

What are Blood Cells and How Do They Work?

Blood consists of plasma and blood cells. The different cells are called: red blood cells, white blood cells, and platelets.

  • Plasma is mostly water with proteins, salts and minerals. It is the fluid that helps carry the nutrients and proteins to the body
  • Red blood cells (RBC) are small, red-colored cells that carry oxygen to all cells of the body
  • White blood cells (WBC) are cells of the immune system. The immune system cells trap and destroy bacteria and other microscopic organisms that might cause us harm. There are several different kinds of WBC, including myeloid cells and two kinds of lymphocytes: T lymphocytes and B lymphocytes
  • Platelets are fragments of blood cells that are needed for blood to clot

Blood cells are made in the bone marrow, the spongy center inside most bones. Most blood cells grow from early cells called stem cells. When the white blood cells mature, they move into the blood vessels where they travel throughout the body.

When we are in good health, the numbers of the different blood cells are kept in proportion to the jobs they do. In the different types of leukemia, too many of a particular blood cell are made, often immature cells called blasts. Blast cells do not fight infection.

Does Leukemia Affect Normal White Blood Cells, Red Blood Cells, and Platelets?

Leukemia can lead to proliferation of malignant white cells in the marrow and reduce the production of normal white cells, red blood cells, and platelets. A low red blood cell count impacts the body's ability to transport oxygen and nutrients, leading to cardiovascular fatigue, dizziness and potentially heart palpitations. Low platelets can lead to easy bruising and bleeding complications, and low white blood cells can increase risk of infections.

What are the Symptoms of Leukemia?

The signs and symptoms of leukemia differ based on the type of leukemia. Early symptoms of leukemia are found most in acute cases. The most common leukemia symptoms include:

  • Fever or chills
  • Persistent fatigue, weakness
  • Frequent infections
  • Frequent bleeding (including nosebleeds) or bruising
  • Loss of weight for no apparent reason
  • Swollen lymph nodes
  • Enlarged liver or spleen
  • Petechiae, small red spots on the skin
  • Excessive night sweating
  • Bone pain

How Is Leukemia Diagnosed?

A leukemia diagnosis starts with a physical examination by a doctor to check lymph nodes, skin petechiae (red spots) and bruising. They typically order a blood test. If further examination is warranted, a doctor may order a bone marrow biopsy or imaging tests. Patients are often diagnosed with leukemia using one or more of the following diagnostic tools:

  • Blood tests: A complete blood count test can show the levels of white blood cells, red blood cells and platelets. Additional blood samples can allow for testing to examine the shape of blood cells and identify abnormalities that may show varying types of leukemia more closely
  • Bone marrow biopsy: Known as a bone marrow aspiration, pulling cells from the bone marrow via a needle for investigation of the cells in a laboratory helps a doctor better understand abnormal cells in the critical area of bone marrow
  • Imaging tests: These could include an X-ray, CT scan or MRI to investigate potential complications of leukemia

Treatment for Leukemia

Leukemia treatment varies based on the type of leukemia, patient age and the spread of the disease. Common treatment approaches include:

  • Chemotherapy: A medication or combination of medications is administered to destroy leukemia cells. Chemotherapy is often done in cycles to allow the body to rest between doses
  • Immunotherapy: Drugs are used to stimulate the body's immune system to find and attack cancer cells. CAR T-cell therapy is a form of immunotherapy
  • Targeted therapy: Specialized drugs are used to target leukemia cells, or alterations within them, and keep them from multiplying
  • Bone marrow transplant: Also known as a stem cell transplant, this procedure replaces cancerous cells with healthy cells taken from the patient's own blood marrow before chemo and radiation or from a blood marrow donor. Healthy stem cells are reintroduced after leukemia cells are killed by chemo and radiation and can grow into new, healthy blood cells

The Mass General Cancer Center approach to leukemia treatment features an internationally recognized level of expertise in all areas of diagnosis and care, including access to clinical trials and state-of-the-art treatment tools. Key pieces of the Mass General approach include consultations with leading doctors specializing in examining tissue samples, access to the Mass General Bone Marrow Transplant Program, a strong understanding of different types of leukemia at the stem cell level, innovative care for newly diagnosed and relapsed patients and compassionate and personalized multi-disciplinary care for all patients.

More information about clinical trials: Find listings of our current clinical trials for leukemia.

Leukemia FAQs

What Causes Leukemia?

The causes of leukemia aren't known, but scientists suspect a combination of environmental and genetic factors. The disease starts with molecular alterations within blood cells, leading to production of abnormal malignant cells, which in turn suppress healthy blood cells in the bone marrow. The lack of healthy white and red blood cells and platelets leads to symptoms of leukemia.

What Are the Risk Factors for Leukemia?

People who develop leukemia may not have any risk factors while others with risk factors may never develop leukemia. Some leukemia risk factors may include:

  • Exposure to chemotherapy or radiation therapy for other forms of cancer
  • Exposure to some chemicals, such as benzene
  • Genetic abnormalities, such as Down syndrome
  • A family history of leukemia
  • Smoking

What Are the Early Signs of Leukemia?

The early symptoms of leukemia are more common in acute cases than in chronic cases. They can include fevers, fatigue, infections, bleeding, bruising, swollen lymph nodes, enlarged liver or spleen, small red spots on the skin, bone pain and excessive night sweating.

How Common Is Leukemia?

While known as a children's cancer, leukemia affects more adults than children as the likelihood of developing leukemia grows with age. Each year, 61,000 new cases of leukemia are diagnosed in the U.S., the 10th most common cancer at 3.5% of all new cases. Leukemia is more common in men and most diagnosed in individuals over 65 years old. For children and teenagers, leukemia accounts for 30% of all cancers.

Can Leukemia Be Cured?

Many types of leukemia are potentially curable. However, often intensive therapy and bone marrow transplant may be needed, and not every patient is a candidate for these intensive treatments due to their age or other medical conditions.

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