Leukemia is cancer of blood-forming tissue such as the bone marrow. Types of leukemia are grouped by the type of cell affected and by the rate of cell growth. Leukemia is either acute or chronic.
Types of Leukemia
There are many different types of leukemia. Some are fast-growing and aggressive, others are slower to progress. Leukemias are also classified based on the type of blood cells affected. The most common types of leukemia include:
Acute leukemia involves an overgrowth of very immature blood cells, also known as blasts. This condition is life-threatening because there are not enough mature blood cells to prevent anemia, infection and bleeding. A diagnosis of acute leukemia is made when there are 20 percent or more blasts in the bone marrow. Acute lymphoblastic leukemia (ALL) is most common during childhood and in early adulthood, although it is also diagnosed in adults 30 years old and older. Acute myelogenous leukemia (AML) occurs more often in adults.
Chronic leukemia involves an overgrowth of mature blood cells. Usually, people with chronic leukemia have enough mature blood cells to prevent serious bleeding and infection. Chronic leukemia is more common in people between ages 40 and 70 and is rare among younger people.
Myelodysplastic Syndrome (MDS) is a condition in which the bone marrow does not function normally and does not produce enough normal blood cells. The blood cells affected are white blood cells, red blood cells and platelets. Some cases of MDS may progress to acute leukemia, over time. MDS is most often found in patients nearing their 60s and 70s.
When your doctor is looking for specific types of leukemia, they will look at chromosome number and appearance, features on the bone marrow cell surface and the appearance of the bone marrow cells under a microscope.
The different types of leukemia share some common symptoms, including:
- Persistent fatigue or feeling of weakness
- Loss of appetite
- Unintentional weight loss
- Easy bruising or bleeding
- Shortness of breath
- Petechiae (tiny red spots under the skin caused by bleeding)
Symptoms of acute lymphoblastic leukemia may also include the presence of painless lumps under the skin in the groin, underarm or neck, and/or pain under the ribs.
The diagnosis of leukemia is based on the results of both blood and bone marrow tests, such as bone marrow aspiration and bone marrow biopsy.
Bone marrow aspiration: Before insertion of the bone marrow aspiration needle, the aspiration site is numbed with anesthesia. During this procedure, a sample of bone marrow cells is removed from the hip bone with a needle. Most people feel pressure as the needle is inserted and a few seconds of sharp pain when the bone marrow fluid is removed.
Bone marrow biopsy: With a bone marrow biopsy, a small piece of bone is removed. A biopsy may be slightly more painful, but only during the procedure.
The most effective treatment for leukemia is chemotherapy, which may involve one or a combination of anticancer drugs that destroy cancer cells. Specific types of leukemia are sometimes treated with radiation therapy or biological therapy. Each type of leukemia is sensitive to different combinations of chemotherapy. Medications and length of treatment vary from person to person. Treatment time is usually from one to two years.
Your treatment may consist of different chemotherapy drugs and biological therapies. The short-term goal is for a complete remission (CR). A complete remission means that the bone marrow has less than 5 percent blasts, the absolute neutrophil counts is over 1,000 and the platelet count is over 100,000.
The long-term goal is for an extended disease-free state and cure.
A course or cycle is the period of time from the start of your chemotherapy until either the blood and bone marrow cell counts are back to normal or when you are able to receive further treatment. In some cases, the leukemia cells are destroyed only from the blood and not from the bone marrow during the first course of chemotherapy. In these cases, a second course may be needed.
If the leukemia does not respond to one or two courses of treatment, a different drug program may be used to bring on a remission. A different drug program may also be used if a relapse occurs.
A specific treatment plan is called a protocol. Each protocol is usually named by letters with each letter standing for a particular drug. A protocol may be considered either standard or experimental therapy. Your doctor will discuss with you the advantages and disadvantages of a particular type of therapy. Once your protocol is determined, you will receive more specific information about the drug(s) that will be used to treat your leukemia. Common side effects of most chemotherapy drugs include hair loss, nausea and vomiting, decreased blood counts and infections.
Radiation therapy is used along with chemotherapy for some kinds of leukemia. Radiation therapy (also called radiotherapy) uses high-energy rays to damage cancer cells and stop them from growing. The radiation comes from a large machine. Radiation therapy for leukemia patients may be given in two ways. For some patients, the doctor may direct the radiation to one specific area of the body where there is a collection of leukemia cells, such as the spleen or testicles. Other patients may receive radiation that is directed to the whole body. This is called total-body irradiation. This type of radiation usually is given before a stem cell transplant.
Biological therapy is sometimes used to treat leukemia. Biological therapies include growth factors, interleukins, monoclonal antibodies, etc. Some patients receive only biological therapy, while others also receive chemotherapy at the same time. You will receive more detailed information about biological therapy if it is used as a treatment for your type of leukemia.
A splenectomy is the surgical removal of the spleen. The spleen is located in the abdomen, on the left side. It acts as a filtration system for blood cells. When a patient has chronic leukemia, the spleen tends to collect leukemia cells, transfused platelets and RBCs. Frequently the spleen enlarges from storing these cells. This makes it difficult for the chemotherapy to reduce the quantity of diseased cells. If the spleen is not removed, it sometimes grows so large that it causes breathing difficulty and compresses other organs. In that case, a splenectomy may be needed.
New treatments are always being tested in clinical trials and some patients with cancer may want to consider participating in one of these research studies. These studies are meant to help improve current cancer treatments or obtain information on new treatments. Talk to your doctor about the clinical trials that may be right for you.