Leukemia is a type of blood cancer that begins in the bone marrow — the soft tissue inside your bones where blood cells are produced. In leukemia, the bone marrow produces abnormal white blood cells that do not function properly, gradually crowding out healthy blood cells and impairing the body's ability to fight infections, carry oxygen, and control bleeding.
Leukemia is classified along two axes: how fast it progresses and which type of white blood cell is affected. Acute leukemias progress rapidly and require immediate treatment, while chronic leukemias develop more slowly and may not need treatment right away. Lymphocytic leukemias affect cells that become lymphocytes (immune system cells), while myelogenous leukemias affect cells that mature into red blood cells, other white blood cells, and platelets.
This classification produces four main types. Acute Lymphocytic Leukemia (ALL) is the most common childhood leukemia but also occurs in adults. Acute Myelogenous Leukemia (AML) is the most common acute leukemia in adults and the second most common in children. Chronic Lymphocytic Leukemia (CLL) is one of the most common adult leukemias, often progressing slowly. Chronic Myelogenous Leukemia (CML) primarily affects adults and is characterized by the Philadelphia chromosome — a specific genetic abnormality.
Risk factors for leukemia include high-dose radiation exposure, repeated exposure to chemicals like benzene, prior chemotherapy treatment, certain genetic conditions such as Down Syndrome, and a strong family history of leukemia. However, many patients develop leukemia without any identifiable risk factors.
Symptoms of leukemia often mimic common illnesses, which can delay diagnosis. According to the American Society of Hematology (ASH), patients may experience fever, chills, night sweats, persistent fatigue and weakness, swollen or bleeding gums, headaches, enlarged liver or spleen, bone or joint pain, pale skin, small red spots on the skin (petechiae), unexplained weight loss, and frequent infections.
Diagnosis begins with a Complete Blood Count (CBC), which may reveal abnormal white blood cell counts, low red blood cells, or low platelets. A peripheral blood smear examined under the microscope can show abnormal cells. A bone marrow biopsy is essential for confirming the diagnosis and determining the specific type. Additional tests including flow cytometry, cytogenetics, and molecular studies provide further classification that guides treatment decisions.
Treatment varies significantly by type. Acute leukemias require aggressive treatment, typically starting with intensive chemotherapy to achieve remission, followed by consolidation therapy to prevent relapse. Chronic leukemias may be managed with targeted therapies — CML, for example, has been transformed by tyrosine kinase inhibitors like imatinib that target the BCR-ABL1 fusion protein. Other treatment options include biological therapy, radiation therapy, stem cell transplantation, and clinical trials.
Advances in molecular diagnostics have revolutionized leukemia treatment. Identifying specific genetic mutations allows doctors to select targeted therapies, predict prognosis, and monitor treatment response with high precision. If you have been diagnosed with leukemia, understanding your specific subtype and molecular profile is essential for optimal treatment planning.