Leukemia is a type of blood cancer that affects blood stem cells in the bone marrow. Instead of maturing into healthy red blood cells, white blood cells, and platelets, the blood stem cells become leukemia cells that multiply rapidly and crowd out healthy blood cells.
Leukemia can be classified as acute or chronic:
Acute leukemia means the affected stem cells cannot mature at all, and the leukemia progresses and spreads quickly.
Chronic leukemia means the stem cells are able to develop partially, but do not function as effectively as healthy mature blood cells. As a result, chronic leukemia tends to be less severe and spread more slowly than acute leukemias.
The diagnosis also depends on the type of blood stem cell affected. Cancer that begins in the myeloid stem cells is considered acute myeloid leukemia (AML) or chronic myeloid leukemia (CML). Cancer that begins in the lymphocyte stem cells is considered acute lymphocytic leukemia (ALL) or chronic lymphocytic leukemia (CLL). Learn more about the types of leukemia here.
Symptoms of Leukemia
Not all people with leukemia experience symptoms. “With acute leukemia, the cells will multiply very quickly, and therefore the majority of the patients will become symptomatic very early,” says Michal Bar-Natan Zommer, MD, hematologist and oncologist at The Mount Sinai Hospital in New York City. Chronic leukemia cells progress slowly, and many patients are asymptomatic for a long period of time.
Symptoms of leukemia may be vague or non-specific, such as:
Several of the symptoms of leukemia are linked to a lack of healthy blood cells (e.g. anemia). Here are common symptoms of leukemia, according to the American Cancer Society:
Leukemia can result in other symptoms if the cancer spreads to other organs, such as a sense of fullness and swelling in the belly (if cancer spreads to the liver or spleen), swollen lymph nodes, joint pain, or coughing and trouble breathing (if cancer spreads to the thymus, an organ behind the breastbone).
How Doctors Diagnose Leukemia
Since not all people with leukemia experience symptoms, catching leukemia early can be a challenge. In those cases, leukemia is often detected during routine blood work, where results may show abnormal counts of red blood cells, white blood cells, or platelets.
These routine blood tests may suggest leukemia, but other tests are necessary to confirm the diagnosis:
A medical history reviews the individual’s symptoms and risk factors for leukemia.
A physical exam may detect swollen organs in which leukemia may have spread (such as lymph nodes or the liver) and signs of infection, bruising, or bleeding.
Blood tests include a complete blood count (which counts each type of blood cell in the blood) and a blood smear (which shows how cells look under a microscope).
Bone marrow tests check a sample for its cellularity, meaning how much of the sample is blood-forming cells. A sample with more blood-forming cells than usual is considered hypercellular, which may indicate leukemia.
Spinal fluid tests take a sample of cerebrospinal fluid, which surrounds the brain and spinal cord, to check if cancer has spread to the central nervous system.
Genetic testing helps look for specific genes or chromosomes linked to leukemia.
Imaging tests do not diagnose leukemia, but they help assess how the leukemia has progressed or spread. CT scans and ultrasounds can show if cancer has spread to the lymph nodes or spleen, and MRIs can see if cancer is affecting the central nervous system (like the brain).
Blood cancers can be complex, and being diagnosed with one may feel overwhelming. Here are questions you should ask your doctor after a blood cancer diagnosis, and here are self-care tips to help cope with blood cancer treatment.