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Leukemia is a cancer of the blood cells that begins in the bone marrow. In many cases, leukemia is not suspected based on symptoms alone, which may resemble those of the flu or other common health conditions. For this reason, there may be delays in diagnosing leukemia. When someone goes to the doctor for general symptoms, a physical exam or blood test may reveal signs that point to leukemia. Often, leukemia is first noticed when routine blood tests show abnormal results. There are no screening exams designed to catch leukemia early.
Once leukemia is suspected, a series of tests are conducted to confirm the diagnosis and subtype of leukemia, establish details that may inform the prognosis and treatment plan, and check for the presence of any complications.
Each type of leukemia can cause specific symptoms that may lead someone to seek health care and a diagnosis. Chronic forms of leukemia may not cause any symptoms in early stages. General symptoms that may occur in any type of leukemia include:
There are two major categories of leukemia. Acute leukemia develops and grows rapidly. Chronic leukemia develops slowly and lasts a long time.
Acute forms of leukemia include acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML). Chronic forms of leukemia include chronic myelogenous leukemia (CML) and chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL).
Acute leukemia is the most common type of cancer in children. Pediatric cancers are usually diagnosed early. Chronic leukemias are most often diagnosed in adults and rarely affect children. There are many subtypes of acute and chronic leukemia. Read more about types of leukemia.
A wide range of tests may be used in the process of diagnosing leukemia. Some tests may lead a doctor initially to suspect leukemia. Others are used to confirm a diagnosis and establish the presence of specific genetic mutations that can influence prognosis and treatment options.
A doctor may notice enlarged lymph nodes, spleen, or liver during a physical examination. If leukemia is suspected, the doctor will gently press their hands into these areas to check for swelling. They may check to see whether your gums are swollen or bleeding. They may look at your skin to check for a tiny sprinkling of red spots known as petechiae.
During the process of taking a medical history, the doctor will likely ask you whether you have experienced any of the symptoms listed above and how long you have had them. You may be asked about potential risk factors, such as smoking cigarettes, exposure to industrial chemicals like benzene or formaldehyde, or past treatment for another type of cancer. Although it is uncommon for leukemia to run in families, your doctor may ask questions about your family history to find out about genetic conditions that could influence the risk. Learn more about leukemia causes and risk factors.
Leukemia is often discovered when routine blood tests return abnormal results, before symptoms arise. Many different tests can be performed on a blood sample. A few of the most common blood tests involved in leukemia diagnosis include:
A CBC assesses the total number of each type of blood cell: red blood cells (RBCs), white blood cells (WBCs), and platelets. A CBC also analyzes hematocrit and hemoglobin levels, which indicate your red blood cells’ ability to carry oxygen around the body. Typically, people with leukemia show above-normal numbers of WBCs and below-normal numbers of RBCs and platelets. Since high WBC counts can also indicate that the body is fighting an infection, further testing is required to confirm the cause. A CBC may also include a white cell differential to check the ratio of different types of WBCs.
Also called a manual differential, a blood smear involves examining blood samples applied to slides under a microscope. A blood smear allows the doctor to see if blood cells have a normal shape and check details about the number of specific types of WBCs. Results may indicate leukemia or a different underlying condition.
Analysis of blood chemistry does not assess blood cells, but substances in the blood, such as proteins, hormones, vitamins, and electrolytes. Blood chemistry results can indicate the severity of the leukemia, and how well organs such as the kidneys or liver are functioning.
Blood or bone marrow samples can be processed through a highly sensitive device called a flow cytometer to obtain specific information about cell characteristics. For instance, it is important to know the ratio of blasts, or immature white blood cells, to mature cells. Flow cytometry can help pinpoint a subtype of leukemia during diagnosis and catch early indications of relapse after treatment.
Some diagnostic tests for leukemia require a sample of bone marrow. Since blood cells develop in the bone marrow, analyzing this tissue can provide doctors with vital insight into the nature and extent of disease. Bone marrow aspiration is a technique used to obtain a sample of liquid bone marrow, while a bone marrow biopsy collects a small amount of bone and solid bone marrow tissue.
Both aspiration and biopsy are performed using a hollow needle. Bone marrow samples are generally taken from the hip bone. Before a bone marrow biopsy, you will be given a local anesthetic to numb the site. You may request a mild sedative to help you stay relaxed. You may experience pain at the site of the biopsy for a few days after the procedure.
Cancer is the result of genetic mutations in specific cells. Researchers have identified a wide variety of genetic variants associated with subtypes of cancer. Identifying these genetic variants helps doctors predict the course of the disease and which treatments are most likely to be effective. Cytogenetic testing of leukemic cells analyzes changes to the chromosomes or genes. Cytogenetic testing is an important part of leukemia diagnosis. Types of cytogenetic testing that may be used in the process of diagnosing leukemia include:
FISH can identify genetic changes to blood cancer cells in samples of blood or bone marrow. It may be used during diagnosis to help select the best treatment plan. During treatment, FISH may be performed every three to six months to monitor the effectiveness of treatment.
Used to identify specific characteristics of leukemia cells, immunophenotyping is another tool that allows doctors to understand exactly what type of leukemia you have and which treatments are likely to work best.
A karyotype test creates a map of the chromosomes in cancer cells to determine specific abnormalities. Karyotyping provides further details that may be used to create a tailored treatment plan.
Some people with leukemia develop complications that affect the lungs, gastrointestinal system, and brain, among other parts of the body. (Read more about conditions related to leukemia.) If your doctor suspects you have developed complications of leukemia, they may order imaging tests including:
Imaging scans are painless and can help identify the extent of leukemia.
Your doctor may order a lumbar puncture to check for the presence of leukemia cells in the cerebrospinal fluid, which bathes the brain and spinal cord. During a lumbar puncture, also known as an LP or spinal tap, a doctor will insert a needle between two vertebrae in the spine to collect a sample of cerebrospinal fluid from the spinal canal.
Todd Gersten, M.D., is a hematologist-oncologist at the Florida Cancer Specialists & Research Institute in Wellington, Florida. Learn more about him here. Review provided by VeriMed Healthcare Network.