What Is Leukemia and How Does It Differ From Other Types of Cancer?

Leukemia is a common blood cancer diagnosis across the world. Globally, blood cancer accounts for about 1.24 million new cancer cases each year. In the U.S., leukemia accounts for 3.1% of all new cancer diagnoses and 3.9% of all cancer-related deaths. In 2024, it’s estimated that there will be 62,770 new cases of leukemia, and approximately 437,337 people in the U.S. are currently living with leukemia or are in remission.

To understand how this disease is burdening the global population and begin to rally for change, it’s important to have a firm grasp on what it is. Leukemia differs from other cancers and has several subtypes.

What Is Leukemia?

Leukemia is a blood cancer affecting the body’s blood-forming tissues, producing an abnormal amount or type of blood cells. It is a malignant disease that affects either the myeloid cells in the bone marrow or the lymphoid cells of the lymphatic system. The origin of the cancer, along with its severity, helps categorize it into subtypes.

Cancer, on a biological level, is when cells begin dividing and moving abnormally. This often presents as tumors, but certain cancers like leukemia do not have visible tumors. Many cancers also metastasize, or spread to other areas of the body. However, leukemia is widespread at diagnosis so it isn’t classified as metastatic.

Instead, leukemia involves hematological malignancies, or cancerous cells in the blood. White blood cells fight off infection in the body and are also called leukocytes, hence the name “leukemia.” However, leukemia can also affect the production of red blood cells, which carry oxygen to other parts of the body, and platelets that clot blood when necessary.

Typically, leukemia is the underproduction or production of immature blood cells. If there are too many blood cells being produced, this is typically classified as a myeloproliferative disorder — which can sometimes evolve into acute leukemia.

The four main types of leukemia are:

• Acute lymphocytic leukemia (ALL);
• Acute myelogenous leukemia (AML);
• Chronic lymphocytic leukemia (CLL);
• Chronic myelogenous leukemia (CML).

All types are named for their origin and their severity. Lymphocytic leukemia originates in the lymphatic system, and myelogenous leukemia originates in the bone marrow.

What Is Acute Leukemia?

Acute leukemia involves the rapid spreading of the disease. Immature blood cells, or blasts, quickly replace normal blood cells, and the progression of the disease moves much faster. Eventually, blood cells aren’t being produced. A lack of white blood cells, platelets, and red blood cells can cause anemia and susceptibility to infections, further complicating the disease.

Chronic leukemia is the slower-moving form of the cancer. The body may still be producing mature blood cells, but there are underdeveloped blasts present. Chronic leukemia typically affects older adults and presents fewer symptoms over a longer period.

Early Signs of Leukemia

Early on, there may not be any apparent signs of leukemia. However, you may notice:

• Aches in bones and joints;
• Cold- or flu-like symptoms;
• Enlarged liver and/or spleen;
• Fatigue;
• Frequent minor infections;
• Headaches;
• Mild fever;
• Night sweats;
• Pallid complexion from anemia;
• Persistent nosebleeds;
• Pinprick-sized dots just under the skin;
• Prolonged bleeding;
• Shortness of breath, particularly upon physical exertion;
• Slow healing of cuts;
• Swollen gums;
• Swollen lymph nodes;
• Unexplained or easy bruising;
• Unintentional weight loss.

These symptoms vary depending on the progression speed of the particular type of leukemia affecting your body. It’s possible to have leukemia and not experience any symptoms until years into the disease.

Other Symptoms of Leukemia

As leukemia progresses, symptoms may worsen. Depending on your prognosis, you may experience some of the following more severe symptoms of leukemia:

• Cold, bluish-tinged skin, especially in the extremities;
• Congestion in airways and lungs;
• Cognitive decline and confusion;
• Decreased urination;
• Dry mouth and lips;
• Hallucinations;
• Restlessness or involuntary movements;
• Loss of bladder and bowel control;
• Slowed breathing.

As leukemia progresses to the final stages, patients are likely to become less and less responsive to external stimuli. This occurs only in severe cases that have progressed past the point where treatment is effective.

Causes of Leukemia

The exact cause of leukemia is unknown, but some findings are correlated with the increased risk for leukemia. Rather than pinpointing one cause, researchers have identified several possible causes for a single cell in your DNA in your bone marrow to change and trigger leukemia. Among these possible causes are:

• Alkylating chemotherapy to treat other forms of cancer;
• Exposure to high levels of radiation;
• Exposure to petrochemicals, like benzene, or herbicides, like Agent Orange;
• Family history of cancer;
• Human immunodeficiency virus (HIV) and human T-lymphotropic virus (HTLV);
• Preexisting blood disorders and genetic disorders;
• Tobacco use;
• Use of certain hair dyes.

It’s believed that a combination of genetic and environmental factors influence the development of leukemia.

How Is Leukemia Diagnosed?

Cancer diagnoses require a complex series of tests and analyses performed by doctors and lab technicians. The patient’s blood panels and other health metrics will show certain indications of cancer. Routine blood tests are called complete blood counts (CBC). These CBCs include metrics like eosinophil (EOS) count, which measures the amount of white blood cells present in your body.

This is the main diagnostic criteria for leukemia, requiring an EOS count of 1.5 x 109/L or above that is consistent over time and the absence of a parasite or allergic reaction that could otherwise cause this spike. Other tests that may be done include:

• Bone marrow aspiration and biopsy;
• Molecular testing for specific gene expression;
• Immunophenotyping to find the specific type of leukemia present;
• Cytogenetics to estimate prognosis and recovery;
• CT scans to look for enlarged lymph nodes or enlarged liver/spleen;
• Electrocardiograms and echocardiograms to evaluate the involvement of the heart.

Other diagnostic criteria include organ involvement due to high EOS count, age, risk factors, and comorbid conditions.

Treatment Options for Leukemia

Leukemia requires cancer treatment and management of symptoms, including:

• Chemotherapy, orally or intravenously;
• Immunotherapy;
• Targeted drug therapy;
• Radiation treatment;
• Stem cell or bone marrow transplants;
• Chimeric antigen receptor (CAR) T-cell therapy.

The above treatments aim to stop the progression of cancer-causing cells. The initial goal is to kill as many leukemic cells as possible and achieve remission. Blood cell counts should return to normal. Doctors will follow up with maintenance therapy or continue more intensive treatments, like CAR T-cell therapy that replaces your T-cells with T-cells bioengineered to fight leukemia, if the cancer cells have returned or progressed.

Who Is Most At Risk for Leukemia?

Some groups may have a higher risk of developing leukemia. Children are more likely to develop ALL, while male adults aged 65 and older are more likely to develop the other types — particularly chronic leukemia. Most often, a family history of leukemia isn’t directly correlated with diagnosis.

However, this may change if you have a close relative affected by the disease. Preexisting conditions like myelodysplastic syndromes and congenital diseases like Down syndrome can also leave you more susceptible to leukemia because of the varying gene expression.

Taking control of your health is the best way to prevent leukemia and other diseases. Symptoms of leukemia can overlap with other conditions. It’s important to discuss any concerns with your doctor and conduct research on leukemia using reputable health and medicine sources.

Disclaimer:

The information provided on this website is for general informational purposes only. It is not intended as medical advice and should not be used as a substitute for professional consultation, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website. If you think you may have a medical emergency, call your doctor or emergency services immediately.