Leukemia is a general term used to describe cancers of the blood caused by abnormal production of blood cells in the bone marrow. The bone marrow is the spongy tissue inside of the bones that produces the different types of blood cells. The three major types of blood cells are white blood cells, red blood cells and platelets. There are two types of white blood cells: myeloid cells, which help directly fight infection, and lymphoid cells, which make up the immune system. Red blood cells carry oxygen to the body’s tissue, while platelets help prevent bleeding. In a healthy bone marrow, there are cells called “blasts”, which are immature cells that develop into normal blood cells.
Acute Lymphoblastic Leukemia (ALL) occurs when there is a rapid overproduction of immature white blood cells called lymphoblasts, which are the precursors of lymphoid cells. This causes a “crowding out” effect on the remainder of the bone marrow, resulting in decreased production of normal blood cells. This can lead to anemia, bleeding, and impairment of the immune system. Occasionally, the lymphoblasts are found primarily in the lymph nodes or thymus instead of the blood or bone marrow. In these cases, the disease is called acute lymphoblastic lymphoma. Treatment is similar for both diseases.
ALL is uncommon in adults with about 5000-6000 cases per year in the U.S. The majority of cases occur in children under the age of 15.
Symptoms of Acute Lymphoblastic Leukemia
Most patients have symptoms due to the lack of normal blood cells and excess of leukemia cells in the body including:
- Recurrent infections
- Weight loss
- Easy bruising or bleeding
- Tiny red spots under the skin or in the mouth (called petechiae)
- Pale skin
- Bone pain
- Shortness of breath
- Abdominal discomfort due to an enlarged liver or spleen
- Lumps in the neck, under the arms or in the groin
Risk factors for developing Acute Lymphoblastic Leukemia
Most patients with ALL do not have any known risk factors. However, possible risk factors include past treatment with chemotherapy or radiation or radiation exposure from atomic bomb fallout, and having certain genetic disorders such as Down syndrome.
How Acute Lymphoblastic Leukemia is diagnosed
A preliminary diagnosis of ALL can often be made by simple microscopic examination of a blood sample. In patients who have symptoms concerning for leukemia, a complete blood count (CBC) can show either a high or low white blood cell count, low red blood cell count (anemia), and low platelet count. The hallmark of ALL on CBC is the presence of lymphoid blasts. To make a final diagnosis, a bone marrow biopsy and aspirate is performed.
Special studies are done on the bone marrow tissue to confirm the presence of lymphoid blasts. Further studies are then performed to determine if there are any abnormalities of the chromosomes in the leukemia cells. Based on patient age and the chromosome and other laboratory findings, patients are categorized into favorable or adverse risk categories. These results will influence treatment options and prognosis. A chest X-ray is also obtained to look for a mass in the chest, as this could influence treatment.
Treatment options for Acute Lymphoblastic Leukemia at Tufts Medical Center
The purpose of receiving treatment is to improve symptoms, increase the chance of cure or prolong survival. Different types of treatments are available. Once diagnosed with ALL, the decision regarding which regimen is right for an individual patient should be made under the guidance of a leukemia specialist. The treatment of ALL is divided into two phases.
Remission Induction Therapy - The first phase is remission induction therapy. The purpose of induction therapy is to eliminate the leukemia cells in the blood, bone marrow and tissues. Induction therapy is given soon after the diagnosis is made, often while the patient remains in the hospital Induction therapy involves a combination of chemotherapy medications, given over the course of several days to a month. . Leukemia cells can quickly learn how to resist chemotherapy, so the medications repeat together in different combinations. Chemotherapy for ALL contain combinations of vincristine, corticosteroids (prednisone or dexamethasone), anthracyclines (such as daunorubicin or doxorubicin), cyclophosphamide, cytarabine, methotrexate, 6-mercaptopurine, etoposide, and/or asparaginase. The goal of this first phase of treatment is to achieve a remission, where the blood counts are normal and there is no visible leukemia in the blood or marrow. However, achieving a remission does not mean the leukemia is cured, and additional therapy is nearly always needed to keep it from returning.
Post-remission Therapy - The next phase is post-remission therapy (also called consolidation or intensification therapy) where the goal is to further clear the body of any hidden leukemia cells that can lead to relapse. There are two main options for post remission therapy: more chemotherapy or an allogeneic bone marrow transplant. In patients with standard risk leukemia, consolidation chemotherapy is usually given. The duration of consolidation chemotherapy depends upon which regimen is used, but can last several months. If a patient has high-risk disease, then an allogeneic stem cell or bone marrow transplant is often recommended. This is a complex process during which a patient’s diseased bone marrow is eradicated and replaced by a matched donor’s healthy stem cells or bone marrow.
Maintenance Therapy - Patients who do not receive a bone marrow transplant will typically receive continuation or maintenance therapy with less intense doses of chemotherapy (often methotrexate, 6-mercaptopurine, and vincristine) and corticosteroids given for one to two years after completing consolidation. Some patients may receive additional cycles of intensive chemotherapy to maintain response to treatment.
All of the above treatments are available through our experts here at Tufts Medical Center in Boston.