Diseases & Conditions
Leukemia is a cancer that develops in bone marrow, the spongy tissue inside most bones. In patients with leukemia, the bone marrow produces abnormal white blood cells. These abnormal cells do not work the same way as healthy white blood cells. Instead, they grow and divide uncontrollably, crowding out and replacing normal cells. Patients with leukemia may feel weak or run down, bruise easily, and get more infections as a result of this disruption in normal blood function.
Treatment for leukemia typically takes place in three phases; each phase involves a unique combination of chemotherapy and medications.
Inside normal bone marrow, immature red blood cells, white blood cells, and platelets multiply, mature, and are released into the blood stream. In some cases, however, genetic mutations cause changes in these cells that can alter this process.
In patients with leukemia, some of the white blood cells in the bone marrow do not fully mature — so they do not function properly. These abnormal cells grow more rapidly than normal cells, and continue growing when they should stop. Over time, they begin to overcrowd the bone marrow, impeding the normal function and growth of healthy blood cells.
Classification of Leukemia
Leukemia is described as being either acute or chronic, based on how quickly it progresses:
- Acute leukemia. Acute leukemia progresses quickly. The condition involves large numbers of immature white blood cells that grow very rapidly. Patients with acute leukemia usually have symptoms and require prompt treatment for the best possible outcome.
- Chronic leukemia. Chronic leukemia progresses very slowly, over the course of years. Patients may not have symptoms for a long time and may only be diagnosed by chance when having a blood test for some other reason. Chronic leukemia involves more mature white blood cells that resemble their normal white blood cell counterparts. Although chronic leukemia progresses slowly, it can be harder to cure than acute leukemia.
Leukemia is further classified by the type of white blood cell that it affects:
- Lymphocytic leukemia. This type of leukemia affects lymphocytes.
- Myelogenous leukemia. This type of leukemia affects myeloid cells.
Types of Leukemia
There are four main types of leukemia:
- Acute lymphoblastic leukemia (ALL)
- Chronic lymphoblastic leukemia (LLL)
- Acute myelogenous leukemia (AML), including acute promyelocytic leukemia (APL)
- Chronic myelogenous leukemia (CML)
Acute lymphoblastic leukemia is the most common type, representing about 80% of all cases. It occurs most often in children and teenagers.
The other three types (LLL, AML, and CML) occur more often in adults — usually in patients who are in their 50s and 60s.
The cause of leukemia is not known. Some things may increase your risk for developing it, however, such as having certain hereditary conditions, being exposed to certain toxins, or having certain types of viral infections.
Symptoms of leukemia vary, depending on the specific type; however, many patients will experience:
- Fatigue, exercise intolerance, and shortness of breath — due to decreased red blood cells (anemia)
- Increased susceptibility to infections — due to decreased production of normal functioning white blood cells
- Easy bruising and bleeding — due to decreased platelet production (thrombocytopenia)
Other signs and symptoms may include:
- Night sweats
- Unintentional weight loss
- Enlarged lymph nodes
- Enlarged spleen
- Bone and joint pain
Although rare, some patients may develop pathologic bone fractures if a tumor weakens the bone. This is more common if the tumor develops in a weight-bearing area of the skeleton like the pelvis, spine, or femur (thighbone).
Your doctor will talk with you about your general health and medical history and ask about your symptoms. They will then perform a physical examination, looking for:
- Enlarged or hard lymph nodes
- Signs of anemia
- Evidence of an enlarged liver or spleen
Your doctor will use blood tests to help diagnose leukemia.
A number of different tests will be used to analyze your blood sample. These tests include:
- Complete blood count with differential. This test identifies and counts the different types of white blood cells present in your blood.
- Flow cytometry. This test looks for cell surface markers that are unique to different types of leukemia.
- Peripheral smear examination. This test looks for abnormalities in the number and shape of your white blood cells.
Other abnormalities that may be identified with blood tests include anemia (low red blood cell count) or thrombocytopenia (low platelet count).
Identifying the stage, or severity, of your leukemia will help your doctor determine the most effective treatment strategy.
Staging is determined by a number of factors, including:
- Findings from blood tests
- Degree of effect on other normal cell lines
- Tissue involvement (with some types)
Treatment for leukemia usually takes place in three phases. Each phase involves different combinations of chemotherapy and medications. Your doctor will consider several factors when determining the appropriate therapies in each phase, including:
- Your age
- The specific type of leukemia
- Whether you have other underlying health conditions
- Your preference for a specific treatment
The three phases of treatment for leukemia typically include:
Induction of Remission. During the first phase of treatment, several anti-cancer medications are used to combat and destroy as many abnormal cells as possible — with the goal of causing the cancer to go into remission. This phase may take months — but is usually over within 1 year.
Consolidation Therapy. Once remission is achieved, treatment focuses on preventing the spread of cancer to other parts of the body. Therapies used in this phase may include additional rounds of chemotherapy, other leukemia-specific medications, or stem cell bone marrow transplantation. This phase is usually complete in under 2 years.
Maintenance Therapy. The third phase of treatment focuses on maintaining cancer remission through some combination of medication and chemotherapy cycling. The length of maintenance therapy varies, depending on the severity of the leukemia.
Novel treatments through clinical studies may also be available for patients who meet certain selection criteria. Your doctor will talk with you about the best course of treatment for your specific situation.
Your outcome after treatment will depend on a number of factors, including:
- Your age
- The specific type of leukemia
- The method of treatment
After treatment, you will meet with your doctor so they can assess your response to therapy. Regular follow-up appointments will also be scheduled so that your doctor can look for signs of treatment complications or recurrence. Recurrence of leukemia is possible even many years after treatment has ended. For this reason, most patients will need many years of follow up.
The prognosis for patients with leukemia is highly variable. Even within specific types, some patients respond well to certain treatments while others do not. Your doctor will talk with you about your specific prognosis.
Contributed and/or Updated by
AAOS does not endorse any treatments, procedures, products, or physicians referenced herein. This information is provided as an educational service and is not intended to serve as medical advice. Anyone seeking specific orthopaedic advice or assistance should consult his or her orthopaedic surgeon, or locate one in your area through the AAOS Find an Orthopaedist program on this website.