What is leukemia?
Leukemia is a malignancy (cancer) of blood cells. Leukemia involves the production of abnormal white blood cells — the cells responsible for fighting infection. However, the abnormal cells in leukemia do not function in the same way as normal white blood cells. The leukemia cells continue to grow and divide, eventually crowding out the normal blood cells. The end result is that it becomes difficult for the body to fight infections, control bleeding, and transport oxygen.
Common types of leukemia
There are different types of leukemia, based upon how quickly the disease develops and the type of abnormal cells produced. Leukemia is called an acute leukemia if it develops rapidly. Large numbers of leukemia cells accumulate very quickly in the blood and bone marrow, leading to symptoms such as tiredness, easy bruising, and susceptibility to infections. Acute leukemia requires fast and aggressive treatment.
Chronic leukemias develop slowly over time. These leukemias may not cause specific symptoms at the beginning of their course. If left untreated, the cells may eventually grow to high numbers, as in acute leukemias causing similar symptoms
- Acute lymphocytic leukemia(ALL, also known as acute lymphoblastic leukemia) is the most common type of leukemia in children, but it can also affect adults. In this type of leukemia, immature lymphoid cells grow rapidly in the blood.
- Acute myeloid leukemia(AML, also called acute myelogenous leukemia) involves the rapid growth of myeloid cells. It occurs in both adults and children
- Chronic lymphocytic leukemia(CLL) is a slow-growing cancer of lymphoid cells that usually affects people over 55 years of age. It almost never occurs in children or adolescents.
- Chronic myeloid leukemia(CML, also known as chronic myelogenous leukemia) primarily affects adults.
What causes leukemia?
For most cancers, researchers are still trying to understand how they are caused. The same is true for leukemia – doctors do not know what causes it. Medical researchers have identified certain risk factors that make leukemia more likely.
- Exposure to radiation is known to increase the risk of developing AML, CML, or ALL.
- Exposure to benzene, used commonly in the chemical industry, increases the risk of leukemia.
- Cigarette smoking is known to increase the risk of developing AML.
- Down syndrome, Li-Fraumeni syndrome, and other medical conditions can increase the risk of developing leukemia.
- Blood disorders known as myelodysplastic syndromes confer an increased risk of developing AML. Human T-cell leukemia virus type 1 (HTLV-1) is a virus that causes a rare type of leukemia.
What are leukemia symptoms and signs?
The symptoms and signs of leukemia depend upon the type of leukemia. As stated earlier, slow-growing or chronic leukemia may not cause any symptoms at the outset, while aggressive or rapidly growing leukemia may lead to severe symptoms.
- Night sweats
- Swollen lymph nodes that are usually painless
- Feelings of fatigue, tiredness
- Easy bleeding or bruising, causing bluish or purplish patches on the skin or tiny red spots on the skin, or recurring nosebleeds
- Frequent infections
- Bone or joint pain
- Weight loss that is otherwise unexplained, or loss of appetite
- Enlargement of the spleen or liver, which can lead to abdominal pain or swelling
- Red spots on the skin (petechiae)
- Skin nodules
If leukemia cells have infiltrated the brain, symptoms such as headaches, seizures, confusion, loss of muscle control, and vomiting can occur.
How do physicians diagnose leukemia?
- Medical History
- Bone Marrow Aspiration and Biopsy
- Lumbar Puncture
Some advanced tests for classification and prognosis:
- Flow Cytometry
- PCR Analysis
What is the treatment for leukemia?
Treatment will typically depend upon the type of leukemia, the patient’s age and health status, as well as whether or not the leukemia cells have spread to the cerebrospinal fluid.
Chemotherapy is the administration of drugs that kill rapidly dividing cells such as leukemia or other cancer cells. Chemotherapy may be taken orally in pill or tablet form, or it may be delivered via a catheter or intravenous line directly into the bloodstream. Combination chemotherapy is usually given, which involves a combination of more than one drug. The drugs are given in cycles with rest periods in between.
Sometimes, chemotherapy drugs for leukemia are delivered directly to the cerebrospinal fluid (known as intrathecal chemotherapy). Intrathecal chemotherapy is given in addition to other types of chemotherapy and can be used to treat leukemia in the brain or spinal cord or, in some cases, to prevent spread of leukemia to the brain and spinal cord.
Side effects of chemotherapy depend on the particular drugs taken and the dosage or regimen. Some side effects from chemotherapy drugs include hair loss, nausea, vomiting, mouth sores, loss of appetite, tiredness, easy bruising or bleeding, and an increased chance of infection due to the destruction of white blood cells. There are medications available to help manage the side effects of chemotherapy.
Some adult men and women who receive chemotherapy sustain damage to the ovaries or testes, resulting in infertility. Most children who receive chemotherapy for leukemia will have normal fertility as adults, but depending on the drugs and dosages used, some may have infertility as adults.
Biological therapy is any treatment that uses living organisms, substances that come from living organisms, or synthetic versions of these substances to treat cancer. Biological therapies for various types of cancer can include antibodies, tumor vaccines, or cytokines (substances that are produced within the body to control the immune system). Monoclonal antibodies are antibodies that react against a specific target that are used in the treatment of many kinds of cancer. Interferons are cell signaling chemicals that have been used in the treatment of leukemia.
Side effects of biological therapies tend to be less severe than those of chemotherapy and can include rash or swelling at the injection site for IV infusions of the therapeutic agents. Other side effects can include headache, muscle aches, fever, or tiredness.
Targeted therapies are drugs that interfere with one specific property or function of a cancer cell, rather than acting to kill all rapidly growing cells indiscriminately. This means there is less damage to normal cells with targeted therapy than with chemotherapy. Targeted therapies may cause the target cell to cease growing rather than to die, and they interfere with specific molecules that promote growth or spread of cancers.
Targeted therapies are given in pill form or by injection. Side effects can include swelling, bloating, and sudden weight gain. Other side effects can include nausea, vomiting, diarrhea, muscle cramps, or rash.
Radiation therapy uses high energy radiation to target cancer cells. Radiation therapy may be used in the treatment of leukemia that has spread to the brain, or it may be used to target the spleen or other areas where leukemia cells have accumulated.
Radiation therapy also causes side effects, but they are not likely to be permanent. Side effects depend on the location of the body that is irradiated. With any radiation therapy, the skin in the area being treated may become red, dry, and tender. Generalized tiredness is also common while undergoing radiation therapy.
Stem cell transplant
In stem cell transplantation, high doses of chemotherapy and/or radiation are given to destroy leukemia cells along with normal bone marrow. Then, transplant stem cells are delivered by an intravenous infusion. The stem cells travel to the bone marrow and begin producing new blood cells. Stem cells may come from the patient or from a donor.
Autologous stem cell transplantation refers to the situation in which the patient’s own stem cells are removed and treated to destroy leukemia cells. They are then returned to the body after the bone marrow and leukemia cells have been destroyed.
An allogeneic stem cells transplant refers to stem cells transplanted from a donor. These may be from a relative or an unrelated donor. A syngeneic stem cell transplant uses stem cells taken from a healthy identical twin of the patient.
Stem cells may be removed (harvested) in different ways. Typically, they are taken from the blood. They can also be harvested from the bone marrow or from umbilical cord blood.
Stem cell transplantation is done in a hospital, and it is necessary to remain in the hospital for several weeks. Risks of the procedure include infections and bleeding due to the depletion of normal blood cells. A risk of stem cell transplant with donor cells is known as graft-versus-host disease (GVHD). In GVHD, the donor white blood cells react against the patient’s normal tissues. GVHD can be mild or very severe, and often affects the liver, skin, or digestive tract. GVHD can occur at any time after the transplant, even years later. Steroids or medications that suppress the immune response may be used to treat this complication.
Because many of the treatments for leukemia deplete normal blood cells, increasing the risk for bleeding and infection, supportive treatments may be needed to help prevent these complications of treatment. Supportive treatments may also be needed to help minimize and manage unpleasant side effects of medical or radiation therapy.
Types of supportive and preventive treatments that can be used for patients undergoing treatment for leukemia include the following:
- Vaccines against the flu or pneumonia
- Blood or platelet transfusions
- Anti-nausea medications
- Antibiotics or antiviral medications to treat or prevent infections
- White blood cell growth factors to stimulate white blood cell production (such as granulocyte-colony stimulating factor [G-CSF], made up of filgrastim [Neupogen] and pegfilgrastim [Neulasta] and granulocyte macrophage-colony stimulating growth factor [GM-CSF], made up of sargramostim [Leukine])
- Red cell growth factors to stimulate red blood cell production (darbepoetin alfa [Aranesp] or epoetin alfa [Procrit])
- Intravenous injections of immunoglobulins to help fight infection