Leukemia: The Basicsby Eileen Bailey Health Writer
What is leukemia?
Leukemia is a cancer of the blood and bone marrow. Abnormal cells in the bone marrow, where blood cells are made, change into leukemia cells. As they grow and multiply, they can crowd out or prevent the development of normal cells. Leukemia most often occurs in adults over the age of 55 but is also the most common cancer in children younger than 15, according to the National Cancer Institute.
Types of leukemia
We categorize leukemia based on which type of white blood cell is involved (lymphocytic or myeloid), and how quickly it develops. Leukemias with fast-growing cells are called “acute;” leukemias with slow-growing cells are called “chronic.” Children rarely get chronic leukemias. The four main types of leukemia are:
Acute Lymphocytic Leukemia (ALL) – This type starts in bone marrow where blood cells are made. Abnormal white blood cells grow and multiple in the bone marrow. It is more common in children than adults.
Acute Myeloid Leukemia (AML) – This type is most common in the elderly. It is also known as acute myelocytic leukemia, acute myelogenous leukemia, acute granulocytic leukemia or acute non-lymphocytic leukemia. It starts in cells that become white blood cells.
Chronic Lymphocytic Leukemia (CLL) – This type accounts for one-third of all leukemias and mainly affects older adults. It starts in white blood cells in the bone marrow (lymphocytes) and is considered chronic because it develops slowly.
Chronic Myeloid Leukemia (CML) – This type starts in blood-forming cells of the bone marrow and then spreads to the blood. It accounts for 10 percent of all leukemias.
While warning signs may vary based on the type of leukemia, common symptoms include
Lack of energy
Shortness of breath during physical activity
Slow healing of cuts
Excess bleeding from cuts
Bruises without any apparent cause
Pinhead-size red spots under the skin
Aches in bones or joints
Low white blood counts
Some people with chronic leukemia experience only mild symptoms or no symptoms at all, and may discover they have leukemia only after a routine blood test. People with chronic lymphocytic leukemia (CLL) may notice enlarged lymph nodes in the neck, armpit, or groin, and have frequent infections. People with chronic myeloid leukemia (CML) may have an enlarged spleen, night sweats, and unexplained weight loss.
Diagnosis and treatment
Diagnosis of leukemia starts with a complete blood count (CBC) test. The doctor is looking for low levels of platelets and red blood cells, either high or low levels of white blood cells, and the possible presence of actual leukemia cells. The next step is a bone marrow aspiration and biopsy which can confirm the diagnosis and identify the leukemia cell type.
Your doctor uses the results of these tests, including your type of leukemia, along with information on your health history to determine a course of treatment. Possible treatments include
Watch and wait – Although it is hard to do nothing, a watch and wait approach may be the best approach for chronic, slow-growing leukemias. During a watch and wait period, you will receive regular screenings to monitor the progress of the disease.
Chemotherapy – Traditional chemotherapy uses one or more drugs to attack and kill the cancer cells. This type of treatment can also kill normal cells and can have serious side effects.
Targeted therapy – This type of treatment uses drugs to target the changes inside the cells rather than attacking rapidly growing cells in general, as standard chemotherapy drugs do.
Radiation therapy – X-rays and high doses of radiation are used to kill the cancer cells. As with traditional chemotherapy, normal and healthy cells can also be attacked, causing serious side effects.
Immunotherapy – A relatively new treatment uses your body’s immune system to fight the cancer.
Vaccine therapy – This treatment does not prevent cancer as the name suggests but is used to strengthen or boost your immune system to fight the cancer cells.
Stem cell transplantation – After high doses of chemotherapy, doctors use cells from the blood, bone marrow, or umbilical cord to restore the bone marrow.
Treatment for leukemia and other types of blood cancer often include a combination of treatments such as chemotherapy, radiation, and stem cell transplantation. Talk to your doctor about the pros and cons of the different types of treatment and which would be best for you.
In addition to these treatments, there are also ongoing clinical trials looking to find new and effective ways to treat leukemia. The National Cancer Institute provides information on clinical trials.
The risk factors and causes of leukemias are mostly unknown.
Exposure to radiation and certain chemicals in the environment, including tobacco smoke, are the main known risk factors for leukemia—especially AML. Having had previous radiation therapy or chemotherapy for other cancers also raises the risk for developing AML. In addition, having a parent, child, or sibling with CLL makes you two to four times more likely to develop CLL yourself. Having Down syndrome, certain other genetic diseases, or bone marrow failure disorders—called myelodysplastic syndromes—can slightly raise the risk for leukemia as well.
However, many people with one or several risk factors never develop leukemia, and, conversely, most people who do develop leukemia have no risk factors that we know of.