leukemia Symptoms, Types, Causes & Treatments
What is leukemia?
Leukemia is a cancer of the blood and bone marrow. In simple terms, cancer is defined as the uncontrolled growth of abnormal cells. Cancer can develop anywhere in the body. In leukemia, this rapid and uncontrolled growth of abnormal cells takes place in the bone marrow of the bones. These abnormal cells then spill into the bloodstream. Unlike other cancers, leukemia usually does not form into a mass (tumor) that can be seen on imaging tests, such as X-rays.
There are many types of leukemia. Some are more common in children; others are more common in adults. Treatment depends on the type of leukemia you have and other factors.
What is bone marrow?
The bone marrow is the soft, spongy tissue found in the central cavity of all bones. It is a limited space where all the different types of blood cells are produced and where nutrients and other resources are supplied to help these cells grow. Blood cells keep our bodies healthy and functioning normally. More specifically, the different types of blood cells produced in the bone marrow include:
Red blood cells. These cells carry oxygen and other materials to all tissues and organs in the body.
White blood cells. These cells fight infection.
Platelets help the blood to clot.
Hundreds of billions of new blood cells are produced in your bone marrow each day, providing your body with a constant supply of fresh, healthy cells.
How does leukemia develop? How does leukemia affect the body?
Leukemia begins in the developing blood cells of the bone marrow. All blood cells start out as hematopoietic stem cells (heme = blood; poiesis = produce). Stem cells go through multiple stages of development until they reach their adult form.
First, the blood stem cells turn into myeloid cells or lymphoid cells. If blood cells continued to develop in a completely normal way, the adult forms of these cells would be as follows:
- Myeloid cells develop into red blood cells, platelets, and certain types of white blood cells (basophils, eosinophils, and neutrophils).
- Lymphoid cells develop into certain types of white blood cells (lymphocytes and natural killer cells).
Then, inside the bone marrow, the blood cells begin to multiply and divide into red blood cells, white blood cells, and platelets. However, if you have leukemia, one of these types of blood cells begins to multiply rapidly, out of control. These abnormal cells, called leukemia cells, begin to occupy the space within the bone marrow. They crowd out the other normal cell types that are trying to develop. This is bad in several ways:
- Unlike other types of blood cells, leukemia cells are abnormal and serve no useful purpose.
- The other types of cells (red blood cells, white blood cells, and platelets) have very little space and support to continue growing and multiplying within the bone marrow.
- This results in fewer normal blood cells being produced and released into the blood and more leukemic cells being produced and released into the blood. Without an adequate number of normal blood cells, your body's organs and tissues won't get the oxygen they need to function properly, your body won't be able to fight infection, or clot your blood when necessary.
Leukemic cells are usually immature (still developing) white blood cells. In fact, the term leukemia comes from the Greek words for "white" (leukos) and "blood" (haima). An excessive number of white blood cells is seen when looking at the blood through a microscope and the actual appearance of the blood is clearer to the naked eye.
Are there different types of leukemia?
Yes. Doctors classify leukemia by how quickly the disease worsens and by the type of blood cell involved.
By speed of disease development:
- Acute leukemia. Leukemic cells divide rapidly and the disease progresses rapidly. If you have acute leukemia, you will feel sick within a few weeks of the leukemia cells forming. Acute leukemia is the most common pediatric cancer.
- Chronic leukemia These leukemic cells often have characteristics of both mature and immature cells. Some of these cells may have developed to the point where they function like the cells they were destined to become, but not to the extent that their normal counterparts do. The disease generally worsens slowly compared to acute leukemia. If you have chronic leukemia, you may not have noticeable symptoms for years. Chronic leukemia is seen more often in adults than in children.
By cell type:
- Myeloid or myeloid leukemia means that leukemia has developed from the myeloid cell line. Normal myeloid cells develop into red blood cells, white blood cells, and platelets.
- Lymphocytic leukemia means that leukemia has developed from the lymphoid cell line. Normal lymphoid cells turn into white blood cells that are an important part of the body's immune system.
There are four main types of leukemia:
- Acute myeloid leukemia (AML): This is the most common type of acute leukemia. It is more common in older adults (over 65) and in men compared to women. About 4.3 per 100,000 men and women or 21,400 new cases of AML per year are diagnosed in the United States.
- Acute lymphocytic leukemia (ALL): This is the most common type of leukemia in children, adolescents, young adults, and up to age 39. About 54% of new cases occur in those under 20 years of age. It is more common in people of Hispanic and white origin. About 1.7 per 100,000 men and women or 5,900 new cases of ALL per year are diagnosed in the United States.
- Chronic myelogenous leukemia (CML): This leukemia is more common in older adults (more common in those over 65 years of age) and in men. It rarely occurs in children. About 1.9 per 100,000 men and women or 8,900 new cases of CML per year are diagnosed in the United States.
- Chronic Lymphocytic Leukemia (CLL): This is the most common chronic leukemia in adults (most common in those over 65). It is more common in men than women and especially in white men. About 4.9 per 100,000 men and women or 20,700 new cases of CLL per year are diagnosed in the United States.
Who gets leukemia? Are certain people at higher risk for developing leukemia?
Although the exact cause of the DNA mutation that leads to leukemia is not fully understood, scientists have discovered certain risk factors that can increase your risk of developing leukemia. These risk factors include:
- Previous cancer treatment with radiation or chemotherapy.
- History of smoking or working with industrial chemicals. Benzene and formaldehyde are known carcinogenic chemicals found in tobacco smoke and in building materials and household chemicals. Benzene is used in the manufacture of plastics, rubbers, dyes, pesticides, medicines, and detergents. Formaldehyde is found in building materials and many household products such as soaps, shampoos, and cleaning products.
- Having a genetic disorder, such as neurofibromatosis, Klinefelter syndrome, Schwachman-Diamond syndrome, or Down syndrome.
Leukemia can happen to anyone. You can get leukemia and not have any of these risk factors. Other people have one or more of these risk factors and never develop leukemia.
You cannot “catch” leukemia from another person. It is not "passed on" from one person to another.
Is leukemia hereditary? Can leukemia be inherited?
Yes, however, this is rare. Genetic disorders like Down syndrome can increase the risk of leukemia. Scientists have also found other genetic mutations that can increase risk. It is not known exactly how much the risk increases. Having a relative in your family with leukemia does not mean that you or members of your family will also develop leukemia. In fact, in most cases, there is no family history of leukemia. However, if you or a family member have a genetic condition, tell your doctor. Your doctor may recommend genetic testing or counseling.
What are the symptoms of leukemia?
Your symptoms depend, in part, on the type of leukemia you have. However, common signs and symptoms include:
- Tired easily, low energy, weakness.
- Pale skin tone
- Fever.
- Easy bruising and bleeding. Nosebleeds and bleeding gums. Small red spots on the skin (called petechiae). Violet spots on the skin.
- Pain and/or tenderness in the bones or joints.
- Swollen lymph nodes in the neck, armpits, groin, or stomach; enlarged spleen or liver.
- Frequent infections
- Unplanned weight loss.
- Night sweats.
- Difficulty breathing.
- Pain or a feeling of fullness under the ribs on the left side.
Keep in mind that if you have a chronic form of leukemia, you may not have any noticeable symptoms in the early stages of this cancer.
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