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, out-of-control growth of abnormal cells takes place in the bone marrow of bones. These abnormal cells then spill into the bloodstream. Unlike other cancers, leukemia generally doesn’t form into a mass (tumor) that can be seen in 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?
Bone marrow is the soft, spongy tissue in the center cavity of all bones. It is a limited space where all the different types of blood cells are made and where nutrients and other resources are supplied to help these cells grow. Blood cells keep our body 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. Platelets help the blood clot.
Hundreds of billions of new blood cells are produced in the 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 in the bone marrow. All blood cells start out as hematopoietic (hemo = blood; poiesis = make) stem cells. The stem cells undergo multiple stages of development until they reach their adult form.
First, blood stem cells develop into either myeloid cells or lymphoid cells. If blood cells were to continue to develop completely normally, the adult forms of these cells are 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).
As stem cells in bone marrow begin to divide and multiply, they develop into all the needed types of blood cells. In patients with leukemia, cell growth goes "haywire," and there is a rapid growth of abnormal white blood cells.
So inside the bone marrow, blood cells are beginning to multiply and divide into red blood cells, white blood cells and platelets. However, if you have leukemia, one of these blood cell types begins to rapidly multiply, in an out-of-control manner. These abnormal cells – called leukemia cells – begin to take over the space inside the bone marrow. They crowd out the other normal cell types that are trying to develop. This is bad in a number of ways:
- Unlike other blood cell types, the leukemia cells are abnormal and serve no useful purpose.
- The other cell types (red blood cells, white blood cells and platelets) have very little space and support to continue to grow and multiply inside the bone marrow.
- This results in fewer normal blood cells being made and released into the blood and more leukemia cells being made and released into the blood. Without an adequate amount of normal blood cells, your body’s organs and tissues will not get the oxygen they need to work properly, your body won’t be able to fight off infection or clot blood when needed.
Leukemia 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 excess number of white blood cells are seen when looking at blood through a microscope and the actual appearance of the blood is lighter 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. The leukemia cells are rapidly dividing and the disease progresses quickly. If you have an acute leukemia, you would feel sick within weeks of the leukemia cells forming. Acute leukemia is the most common pediatric cancer.
- Chronic leukemia. Often, these leukemia cells have features of both immature and mature cells. Some of these cells may have developed to the point where they do function as the cells they were meant to become, but not to the extent their normal counterparts do. The disease typically worsens slowly as compared to acute leukemia. If you have chronic leukemia, you may not have noticeable symptoms for years. Chronic leukemia is more commonly seen in adults as compared to children.
By cell type:
- Myelogenous or myeloid leukemia means the leukemia has developed from the myeloid cell line. Normal myeloid cells develop into red blood cells, white blood cells and platelets.
- Lymphocytic leukemia means the leukemia has developed from the lymphoid cell line. Normal lymphoid cells develop into white blood cells that are an important part of the body’s immune system.
There are four major types of leukemia:
- Acute myeloid leukemia (AML): This is the most common type of acute leukemia. It is more common in older adults (those over 65 years of age) and in men compared with 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, teens, young adults and those up to 39 years of age. About 54% of new cases occur in those under the age of 20. It is more common in persons 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 (most 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 years of age). 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.
In addition to these four main types of leukemia, there also are various subtypes of leukemia. Subtypes of lymphocytic leukemia include hairy cell, Waldenstrom’s macroglobulinemia, prolymphocytic, and lymphoma cell leukemia. Among the subtypes of myelogenous leukemia are myelogenous, promyelocytic, monocytic, erythroleukemia, and megakaryocytic leukemia.
How common is leukemia?
The number of new cases of leukemia diagnosed in the United States each year is about 14 per 100,000 men and women or 61,000 new cases per year. It is the tenth most common cancer according to new cases diagnosed each year. Leukemia accounts for 3.5% of all new cancer cases in the United States.
Leukemia is often considered a disease of children, yet it actually affects far more adults. In fact, the likelihood of developing this cancer increases with age. Leukemia is most frequently diagnosed in people 65 to 74 years of age. Leukemia is more common in men than in women, and more common in Caucasians than in African-Americans. Although leukemia is rare in children, of the children or teens who develop any type of cancer, 30% will develop some form of leukemia.
Symptoms and Causes
What causes leukemia?
Leukemia starts when the DNA of a single cell in the bone marrow changes (mutates) and can’t develop and function normally. (DNA is the “instruction code” for the cell’s growth and function. Segments of DNA make up genes, which are arranged on larger structures called chromosomes.) All cells that arise from that initial mutated cell also have the mutated DNA.
What causes the damage to the DNA in the first place is still not known in all cases. Scientists have been able to locate changes in certain chromosomes of patients diagnosed with different types of leukemia.
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 known, scientists have discovered certain risk factors that may 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 cancer-causing chemicals found in tobacco smoke and building materials and household chemicals. Benzene is used in the making of plastics, rubbers, dyes, pesticides, drugs 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 may get leukemia and have none of these risk factors. Other people have one or more of these risk factors and never get leukemia.
You cannot “catch” leukemia from someone else. It is not “transmitted” from one person to another.
Does leukemia run in families? Can leukemia be inherited?
Yes, however this is uncommon. Genetic disorders such as Down syndrome can increase the risk of leukemia. Scientists have also found other genetic mutations that can increase the risk. How much the risk is increased is not exactly known. Having a relative in your family with leukemia does not mean you or your family members will also develop leukemia. In fact, in most cases, there’s no family history of leukemia. However, if you or a family member has 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 what type of leukemia you have. However, common signs and symptoms include:
- Tire easily, little energy, weakness.
- Pale skin tone.
- Easy bruising and bleeding. Nosebleeds and bleeding gums. Tiny red spots in skin (called petechiae). Purplish patches in the skin.
- Bone or joint pain and/or tenderness.
- Swollen lymph nodes in the neck, underarm, groin or stomach; enlarged spleen or liver.
- Frequent infections.
- Unplanned weight loss.
- Night sweats.
- Shortness of breath.
- Pain or full feeling 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.
Diagnosis and Tests
How is leukemia diagnosed?
Your doctor will conduct a physical exam, order blood tests and, if results are suspicious, order imaging tests and a bone marrow biopsy.
Physical exam: Your doctor will ask about any symptoms you are experiencing and check for swollen lymph nodes. (You have lymph nodes throughout your body but some can be more easily felt, such as those in your neck or under your armpits). Your doctor may also look at your gums to see if they are swollen or bleeding, look for bruises or a tiny red skin rash (petechiae) and signs of an enlarged spleen. You may not have many or any obvious symptoms if you have early-stage chronic leukemia. Symptoms can also be relatively common to many other illnesses, such as simply feeling tired or having flu-like symptoms that do not improve.
Complete blood count (CBC): This blood test gives details about red blood cells, white blood cells and platelets. If you have leukemia you will have lower than normal counts of red blood cells and platelets, and higher than normal counts of white blood cells. Some leukemia cells may be found. (Leukemia cells are the still developing immature cells – usually white blood cells – that rapidly multiply in bone marrow and spill over into the bloodstream.)
Blood cell examination. Other blood samples may be taken and checked for type and shape of blood cells and examined for other substances released by your body’s organs and tissues that may be signs of disease. Other tests may help identify chromosomal abnormalities and other markers on the cells that help identify the type of leukemia.
Bone marrow biopsy (also called bone marrow aspiration): If your white blood cell count is abnormal, your doctor will get a sample of cells from your bone marrow. During this procedure, a long needle is used to draw out some fluid from the marrow of your bone, usually from an area near your hip (pelvic bone). A laboratory then examines the blood cells in the fluid under a microscope. A bone marrow biopsy helps determine the percentage of abnormal cells in the bone marrow, which confirms the diagnosis of leukemia.
During a bone marrow biopsy, fluid is removed from the bone marrow and examined under a microscopic.
Imaging and other tests: Your doctor may order a chest X-ray, CT scan, or magnetic resonance imaging (MRI) scan if you have symptoms that indicate a complication of the leukemia. A lumbar puncture (also called a spinal tap) may be ordered to see if the cancer had spread to the spinal fluid surrounding the brain and spinal cord.
Management and Treatment
How is leukemia treated?
Treatments for leukemia depend on the type of leukemia you have, your age and overall health, and if the leukemia has spread to other organs or tissues. There are five common treatment categories. They include:
- Chemotherapy: Chemotherapy are chemicals (medications) given in pill form, administered through an IV into a vein or a central line or given in shots under the skin (subcutaneously). The chemicals kill leukemia cells or stop them from dividing. Usually a combination of chemotherapy drugs are used. This is the most common form of treatment for leukemia. Treatment consists of cycles – a certain number of days of treatment are followed by days of rest to allow the body to recover. The length of time for treatment can vary by regimen ranging from six months to indefinite treatment.
- Radiation therapy: This treatment uses strong beams of energy to kill leukemia cells or stop them from growing. Radiation is directed to exact sites in your body where there is a collection of cancer cells or can be given over your whole body as part of a hematopoietic cell transplant (see below).
- Immunotherapy: This treatment, also called biologic therapy, uses certain drugs to boost your body’s own defense system – your immune system – to fight leukemia. Immunotherapies include interferon, interleukins and CAR-T cell therapy.
- Targeted therapy: This treatment uses drugs that are focused on a specific features of leukemia cells. Targeted therapies work by blocking the ability of leukemia cells to multiply and divide, cutting off the blood supply needed for the cells to live, or killing the cells directly. Targeted therapy is less likely to harm normal cells. Examples of targeted therapy include monoclonal antibodies (such as inotuzumab [Besponsa®], gemtuzumab, [Mylotarg®], rituximab [Rituxan®], ofatumumab [Arzerra®], obinatuzumab [Gazyva®, Gazyvaro®], alemtuzumab [Campath®, MabCampath®]) and tyrosine kinase inhibitors (such as imatinib [Gleevec®], dasatinib [Sprycel®], nilotinib [Tasigna®], ponatinib [Iclusig®]), ruxolitinib [Jakafi®], fedratinib [Inrebic®], gilteritinib [Xospata®], midostaurin [Rydapt®], ivositinib [Tibsovo®], ibrutinib [Imbruvica®], venetoclax [Venclexta®]).
- Hematopoietic cell transplant (also known as stem cell or bone marrow transplant): This procedure replaces the cancerous blood-forming cells that have been killed by chemotherapy and/or radiation therapy with new, healthy hematopoietic cells. These healthy cells are taken from you (before exposure to chemo or radiation therapy) or from a donor’s blood or bone marrow and are infused back into your blood. Healthy hematopoietic cells grow and multiply forming new bone marrow and blood cells that develop into all the different types of cells your body needs (red blood cells, white blood cells and platelets). In the case where the cells are taken from a different person (donor), the new immune system recognizes the cancer cells as foreign and kills them (similar to other immunotherapies).
Note: A treatment plan will be developed specifically for you. Several of the treatment methods described above will be a part of your treatment plan. Your treatment depends on your age, overall health, type of leukemia and other unique features of the leukemia, response to initial treatment and many other factors. Your healthcare team will determine a treatment plan they hope will be most successful for you.
What are the stages of leukemia treatment?
Some leukemia treatment is delivered in three phases. Each phase has a specific goal.
- Induction therapy is the first phase. Its goal is to kill as many leukemia cells as possible in the blood and bone marrow to achieve remission. In remission, blood cell counts return to normal levels, no leukemia cells are found in the blood and all signs and symptoms of disease are gone. Induction therapy usually lasts four to six weeks.
- Consolidation (also called intensification), the second phase, begins after leukemia is in remission. The goal of this phase is to kill any remaining undetected leukemia cells in the body so the cancer does not return. Consolidation therapy is usually given in cycles over four to six months.
- Maintenance therapy is given to kill any leukemia cells that may have survived the first two treatment phases. The goal of maintenance therapy is to prevent the return of leukemia (relapse). Treatment usually lasts for about two years.
(Treatment can be also directed at the brain and spinal cord [the central nervous system] during each of these phases. This is done to kill cancer cells that hide in these areas of the body where the chemotherapy cannot reach. These “hidden” cancer cells are a reason leukemia comes back or relapses.)
Other leukemia treatments do not have phases and are given indefinitely. They are continued as long as they are working to combat the leukemia and the patient is tolerating the treatment well.
Treatment is resumed or changed if leukemia comes back or relapses.
Outlook / Prognosis
What outcome can I expect if I have a diagnosis of leukemia?
While this seems like a straight-forward question, the answer is a little more complicated. It’s understandable that you want to know if you or your loved one will survive a diagnosis of leukemia. Unfortunately, it’s difficult to make general predictions. There are many factors to consider that affect your chance of recovery, including:
- Chromosomal abnormalities or mutations. The genetic alterations seen inside of leukemia cells are the most important predictor of outcome.
- Age. Generally, the younger the patient is at the time of diagnosis, the better the outcome.
- Patient’s general health. The better the overall health, the better the outcome.
- Type of blood cell/subtype of leukemia involved.
- Red blood cell, white blood cell and platelet blood counts at time of diagnosis.
- Response to initial treatment: Is the leukemia in remission? Has the leukemia been treated before and has now come back? Did the leukemia not respond to treatment?
- Collection of leukemia cells in areas not easily reached by chemotherapy. This is the case when the leukemia cells are found in the spinal fluid.
The general good news is that although the number of new cases of leukemia in the United States has remained relatively steady or slightly increased since the 1970s, survival rate has also improved.
The National Cancer Institute reports the following survival data for the four main types of leukemia:
|Types of Leukemia||ALL||AML||CLL||CML|
|5- year survival rate*||68.60%||28.30%||85.10%||69.20%|
|Number of deaths per 100,000 persons||0.4||2.8||1.2||0.3|
|Death is highest among those aged||65-74||65+||75+||75+|
ALL = acute lymphocytic leukemia; AML = acute myelogenous leukemia; CLL = chronic lymphocytic leukemia; CML = chronic myelogenous leukemia
* survival compares patients diagnosed with cancer vs people of same age, race and sex who are cancer free.
Data source: SEER Cancer Statistics Review, 1975-2016, National Cancer Institute. Bethesda, MD.
It’s important to keep in mind that treatment results and long-term outcome vary for each patient.
Can leukemia be cured?
From a scientific standpoint, “cured” is a hopeful goal, yet is somewhat difficult to define in the field of cancer. Are you “cured” after five years of being free of cancer? After 10 years? Does cure mean that you no longer have any negative effects on the quality of your life from your treatment?
Cancer researchers usually are more comfortable talking about achieving long-term remission if you have a diagnosis of cancer. Children and teens, younger adults, people in good health with few other illnesses generally have the best outcomes. Acute lymphoid leukemia represents one of the most dramatic success stories in cancer treatment. According to the Leukemia & Lymphoma Society, nearly 90% of children and 40% of adults diagnosed with ALL can expect a long-term remission.
The answer to “am I cured of my leukemia” will best be answered by your healthcare team over a long period of time. Your team will work closely with you to develop the best treatment plan for your specific type of leukemia and will carefully follow you for many years to come.
How often will I need to see my healthcare team after treatment?
It’s important not to miss any of your follow-up appointments. You healthcare team will tell you when and how often you will need to be seen. Follow-up appointments can help manage treatment side effects, check how well treatment is working and make any needed changes in treatment based on a repeat of many of the same tests you took to diagnose the leukemia.
What questions should I ask my doctor and healthcare team after I’ve been diagnosed with leukemia?
Talk with your doctor and members of your healthcare team about your diagnosis of leukemia. Each case of leukemia in each patient is unique. Take notes and/or bring a friend with you to help take notes and provide support. If you don’t understand something a doctor says to you, ask the doctor to explain it. Your healthcare team wants you to play an active role in your care or care of your loved one with leukemia.
Some of the questions to ask your doctor and team may include:
- What type of leukemia do I have? In what type of cell? Is it a fast- or slow-growing kind of cancer?
- How early was the leukemia discovered?
- What are my treatment options?
- What are the benefits and risks of each type of treatment?
- What treatment plan is best suited for me? Why?
- When should treatment begin?
- How long will treatment (and each stage of treatment) last?
- How long will I be in the hospital?
- What are the side effects of treatment? What can be done to prevent or lessen these side effects?
- What if I want to have children? What are my options for preserving my fertility?
- What’s the success rate/survival rate for my type of leukemia?
- Should I enroll in a clinical trial?
Are there clinical trials for leukemia?
Yes. To learn more about clinical trials for leukemia, visit these sites:
- Leukemia & Lymphoma Society Clinical Trial Support Center.
- National Cancer Institute. Clinical Trials Information for Patients and Caregivers.
- American Cancer Society. Clinical Trials.
- National Institutes of Health. Clinical Trials.gov.
- Cancer Trials at Cleveland Clinic.
To find support groups, visit:
- Leukemia & Lymphoma Society. Search for local chapter.
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