Leukemia is cancer that starts in the tissue that forms blood. To understand cancer, it helps to know how normal blood cells form.
Most blood cells develop from cells in the bone marrow called stem cells. Bone marrow is the soft material in the center of most bones.
Stem cells mature into different kinds of blood cells. Each kind has a special job:
White blood cells, red blood cells, and platelets are made from stem cells as the body needs them. When cells grow old or get damaged, they die, and new cells take their place.
First, a stem cell matures into either a myeloid stem cell or a lymphoid stem cell:
The white blood cells that form from myeloid blasts are different from the white blood cells that form from lymphoid blasts.
Most blood cells mature in the bone marrow and then move into the blood vessels. Blood flowing through the blood vessels and heart is called the peripheral blood.
In a person with leukemia, the bone marrow makes abnormal white blood cells. The abnormal cells are leukemia cells.
Unlike normal blood cells, leukemia cells don’t die when they should. They may crowd out normal white blood cells, red blood cells, and platelets. This makes it hard for normal blood cells to do their work.
Types of Leukemia
The types of leukemia can be grouped based on how quickly the disease develops and gets worse. Leukemia is either chronic (which usually gets worse slowly) or acute (which usually gets worse quickly):
Chronic leukemia: Early in the disease, the leukemia cells can still do some of the work of normal white blood cells. People may not have any symptoms at first. Doctors often find chronic leukemia during a routine checkup – before there are any symptoms.
Slowly, chronic leukemia gets worse. As the number of leukemia cells in the blood increases, people get symptoms, such as swollen lymph nodes or infections. When symptoms do appear, they are usually mild at first and get worse gradually.
Acute leukemia: The leukemia cells can’t do any of the work of normal white blood cells. The number of leukemia cells increases rapidly. Acute leukemia usually worsens quickly.
The types of leukemia also can be grouped based on the type of white blood cell that is affected. Leukemia can start in lymphoid cells or myeloid cells. See the picture of these cells. Leukemia that affects lymphoid cells is called lymphoid, lymphocytic, or lymphoblastic leukemia. Leukemia that affects myeloid cells is called myeloid, myelogenous, or myeloblastic leukemia.
There are four common types of leukemia:
When you’re told that you have cancer, it’s natural to wonder what may have caused the disease. No one knows the exact causes of leukemia. Doctors seldom know why one person gets leukemia and another doesn’t. However, research shows that certain risk factors increase the chance that a person will get this disease.
The risk factors may be different for the different types of leukemia:
Having one or more risk factors does not mean that a person will get leukemia. Most people who have risk factors never develop the disease.
Like all blood cells, leukemia cells travel through the body. The symptoms of leukemia depend on the number of leukemia cells and where these cells collect in the body.
People with chronic leukemia may not have symptoms. The doctor may find the disease during a routine blood test.
People with acute leukemia usually go to their doctor because they feel sick. If the brain is affected, they may have headaches, vomiting, confusion, loss of muscle control, or seizures. Leukemia also can affect other parts of the body such as the digestive tract, kidneys, lungs, heart, or testes.
Common symptoms of chronic or acute leukemia may include:
Most often, these symptoms are not due to cancer. An infection or other health problems may also cause these symptoms. Only a doctor can tell for sure. Anyone with these symptoms should tell the doctor so that problems can be diagnosed and treated as early as possible.
Doctors sometimes find leukemia after a routine blood test. If you have symptoms that suggest leukemia, your doctor will try to find out what’s causing the problems. Your doctor may ask about your personal and family medical history.
You may have one or more of the following tests:
There are two ways your doctor can obtain bone marrow. Some people will have both procedures during the same visit:
The tests that your doctor orders for you depend on your symptoms and type of leukemia. You may have other tests:
You may want to ask your doctor these questions before having a bone marrow aspiration or biopsy:
People with leukemia have many treatment options. The options are watchful waiting, chemotherapy, targeted therapy, biological therapy, radiation therapy, and stem cell transplant. If your spleen is enlarged, your doctor may suggest surgery to remove it. Sometimes a combination of these treatments is used.
The choice of treatment depends mainly on the following:
People with acute leukemia need to be treated right away. The goal of treatment is to destroy signs of leukemia in the body and make symptoms go away. This is called a remission. After people go into remission, more therapy may be given to prevent a relapse. This type of therapy is called consolidation therapy or maintenance therapy. Many people with acute leukemia can be cured.
If you have chronic leukemia without symptoms, you may not need cancer treatment right away. Your doctor will watch your health closely so that treatment can start when you begin to have symptoms. Not getting cancer treatment right away is called watchful waiting.
When treatment for chronic leukemia is needed, it can often control the disease and its symptoms. People may receive maintenance therapy to help keep the cancer in remission, but chronic leukemia can seldom be cured with chemotherapy. However, stem cell transplants offer some people with chronic leukemia the chance for cure.
Your doctor can describe your treatment choices, the expected results, and the possible side effects. You and your doctor can work together to develop a treatment plan that meets your medical and personal needs.
You may want to talk with your doctor about taking part in a clinical trial, a research study of new treatment methods.
Your doctor may refer you to a specialist, or you may ask for a referral. Specialists who treat leukemia include hematologists, medical oncologists, and radiation oncologists. Pediatric oncologists and hematologists treat childhood leukemia. Your health care team may also include an oncology nurse and a registered dietitian.
Whenever possible, people should be treated at a medical center that has doctors experienced in treating leukemia. If this isn’t possible, your doctor may discuss the treatment plan with a specialist at such a center.
Before treatment starts, ask your health care team to explain possible side effects and how treatment may change your normal activities. Because cancer treatments often damage healthy cells and tissues, side effects are common. Side effects may not be the same for each person, and they may change from one treatment session to the next.
You may want to ask your doctor these questions before you begin treatment:
People with chronic lymphocytic leukemia who do not have symptoms may be able to put off having cancer treatment. By delaying treatment, they can avoid the side effects of treatment until they have symptoms.
If you and your doctor agree that watchful waiting is a good idea, you’ll have regular checkups (such as every 3 months). You can start treatment if symptoms occur.
Although watchful waiting avoids or delays the side effects of cancer treatment, this choice has risks. It may reduce the chance to control leukemia before it gets worse.
You may decide against watchful waiting if you don’t want to live with an untreated leukemia. Some people choose to treat the cancer right away.
If you choose watchful waiting but grow concerned later, you should discuss your feelings with your doctor. A different approach is nearly always available.
You may want to ask your doctor these questions before choosing watchful waiting:
Many people with leukemia are treated with chemotherapy. Chemotherapy uses drugs to destroy leukemia cells.
Depending on the type of leukemia, you may receive a single drug or a combination of two or more drugs.
You may receive chemotherapy in several different ways:
Intrathecal chemotherapy is used because many drugs given by IV or taken by mouth can’t pass through the tightly packed blood vessel walls found in the brain and spinal cord. This network of blood vessels is known as the blood-brain barrier.
Chemotherapy is usually given in cycles. Each cycle has a treatment period followed by a rest period.
You may have your treatment in a clinic, at the doctor’s office, or at home. Some people may need to stay in the hospital for treatment.
The side effects depend mainly on which drugs are given and how much. Chemotherapy kills fast-growing leukemia cells, but the drug can also harm normal cells that divide rapidly:
People with chronic myeloid leukemia and some with acute lymphoblastic leukemia may receive drugs called targeted therapy. Imatinib (Gleevec) tablets were the first targeted therapy approved for chronic myeloid leukemia. Other targeted therapy drugs are now used too.
Targeted therapies use drugs that block the growth of leukemia cells. For example, a targeted therapy may block the action of an abnormal protein that stimulates the growth of leukemia cells.
Side effects include swelling, bloating, and sudden weight gain. Targeted therapy can also cause anemia, nausea, vomiting, diarrhea, muscle cramps, or a rash. Your health care team will monitor you for signs of problems.
Some people with leukemia receive drugs called biological therapy. Biological therapy for leukemia is treatment that improves the body’s natural defenses against the disease.
One type of biological therapy is a substance called a monoclonal antibody. It’s given by IV infusion. This substance binds to the leukemia cells. One kind of monoclonal antibody carries a toxin that kills the leukemia cells. Another kind helps the immune system destroy leukemia cells.
For some people with chronic myeloid leukemia, the biological therapy is a drug called interferon. It is injected under the skin or into a muscle. It can slow the growth of leukemia cells.
You may have your treatment in a clinic, at the doctor’s office, or in the hospital. Other drugs may be given at the same time to prevent side effects.
The side effects of biological therapy differ with the types of substances used, and from person to person. Biological therapies commonly cause a rash or swelling where the drug is injected. They also may cause a headache, muscle aches, a fever, or weakness. Your health care team may check your blood for signs of anemia and other problems.
You may want to ask your doctor these questions before having chemotherapy, targeted therapy, or biological therapy:
Radiation therapy (also called radiotherapy) uses high-energy rays to kill leukemia cells. People receive radiation therapy at a hospital or clinic.
Some people receive radiation from a large machine that is aimed at the spleen, the brain, or other parts of the body where leukemia cells have collected. This type of therapy takes place 5 days a week for several weeks. Others may receive radiation that is directed to the whole body. The radiation treatments are given once or twice a day for a few days, usually before a stem cell transplant.
The side effects of radiation therapy depend mainly on the dose of radiation and the part of the body that is treated. For example, radiation to your abdomen can cause nausea, vomiting, and diarrhea. In addition, your skin in the area being treated may become red, dry, and tender. You also may lose your hair in the treated area.
You are likely to be very tired during radiation therapy, especially after several weeks of treatment. Resting is important, but doctors usually advise patients to try to stay as active as they can.
Although the side effects of radiation therapy can be distressing, they can usually be treated or controlled. You can talk with your doctor about ways to ease these problems.
It may also help to know that, in most cases, the side effects are not permanent. However, you may want to discuss with your doctor the possible long-term effects of radiation treatment.
You may want to ask your doctor these questions before having radiation therapy:
Some people with leukemia receive a stem cell transplant. A stem cell transplant allows you to be treated with high doses of drugs, radiation, or both. The high doses destroy both leukemia cells and normal blood cells in the bone marrow. After you receive highdose chemotherapy, radiation therapy, or both, you receive healthy stem cells through a large vein. (It’s like getting a blood transfusion.) New blood cells develop from the transplanted stem cells. The new blood cells replace the ones that were destroyed by treatment.
Stem cell transplants take place in the hospital. Stem cells may come from you or from someone who donates their stem cells to you:
Stem cells come from a few sources. The stem cells usually come from the blood (peripheral stem cell transplant). Or they can come from the bone marrow (bone marrow transplant). Another source of stem cells is umbilical cord blood. Cord blood is taken from a newborn baby and stored in a freezer. When a person gets cord blood, it’s called an umbilical cord blood transplant.
After a stem cell transplant, you may stay in the hospital for several weeks or months. You’ll be at risk for infections and bleeding because of the large doses of chemotherapy or radiation you received. In time, the transplanted stem cells will begin to produce healthy blood cells.
Another problem is that graft-versus-host disease (GVHD) may occur in people who receive donated stem cells. In GVHD, the donated white blood cells in the stem cell graft react against the patient’s normal tissues. Most often, the liver, skin, or digestive tract is affected. GVHD can be mild or very severe. It can occur any time after the transplant, even years later. Steroids or other drugs may help.
You may want to ask your doctor these questions before having a stem cell transplant:
Before starting treatment, you might want a second opinion about your diagnosis and treatment plan. Some people worry that the doctor will be offended if they ask for a second opinion. Usually the opposite is true. Most doctors welcome a second opinion. And many health insurance companies will pay for a second opinion if you or your doctor requests it.
If you get a second opinion, the doctor may agree with your first doctor’s diagnosis and treatment plan. Or the second doctor may suggest another approach. Either way, you have more information and perhaps a greater sense of control. You can feel more confident about the decisions you make, knowing that you’ve looked at your options.
It may take some time and effort to gather your medical records and see another doctor. In most cases, it’s not a problem to take several weeks to get a second opinion. The delay in starting treatment usually won’t make treatment less effective. To make sure, you should discuss this delay with your doctor. Some people with leukemia need treatment right away.