What is Leukemia?

• Leukemia is a cancer of the blood-forming tissues, characterized by the overproduction of abnormal white blood cells.
• Symptoms can be vague, including fatigue, frequent infections, easy bruising, and unexplained weight loss, making early recognition challenging.
• The disease is broadly categorized into acute or chronic forms, and myeloid or lymphoid types, each with distinct characteristics and progression rates.
• Diagnosis involves a series of tests, including blood counts, bone marrow biopsies, and genetic analyses, to accurately identify the specific type.
• Treatment options range from chemotherapy and radiation to targeted therapies and stem cell transplantation, tailored to the individual’s specific leukemia type and overall health.

Leukemia is a cancer of the body’s blood-forming tissues, including the bone marrow and the lymphatic system. It primarily affects white blood cells, which are crucial components of the immune system. In leukemia, the bone marrow produces abnormal white blood cells that do not function properly and outnumber healthy blood cells, impairing the body’s ability to fight infection and perform other vital functions. Understanding what is leukemia involves recognizing this fundamental disruption in blood cell production.

Leukemia originates when blood cells in the bone marrow acquire mutations in their DNA. These mutations cause the cells to grow and divide uncontrollably, failing to mature properly. Instead of dying off as normal cells do, these abnormal cells accumulate, crowding out healthy white blood cells, red blood cells, and platelets. This overpopulation of dysfunctional cells leads to the characteristic symptoms of the disease, as the body struggles to perform essential functions like oxygen transport, infection fighting, and blood clotting.

While the exact causes of leukemia are not always clear, several factors can increase an individual’s risk. These include genetic predispositions, such as certain inherited syndromes like Down syndrome. Exposure to certain chemicals, like benzene, or high doses of radiation, can also elevate risk. Additionally, some prior cancer treatments, such as chemotherapy and radiation, can increase the likelihood of developing secondary leukemia. Smoking is another identified risk factor, particularly for acute myeloid leukemia. However, it is important to note that many people with leukemia have no identifiable risk factors.

The leukemia symptoms and signs can vary widely depending on the type of leukemia, its progression, and the individual’s overall health. Because these symptoms often mimic those of less serious conditions, they can be easily overlooked. However, persistent or worsening symptoms warrant medical attention. Common indicators arise from the bone marrow’s inability to produce enough healthy blood cells.

Symptoms related to a lack of healthy red blood cells (anemia) include:

• Persistent fatigue and weakness
• Pale skin
• Shortness of breath during physical activity

Symptoms related to a lack of functional white blood cells (impaired immunity) include:

• Frequent or severe infections
• Fever and chills

Symptoms related to a lack of platelets (impaired clotting) include:

• Easy bruising or bleeding
• Petechiae (tiny red spots on the skin)
• Nosebleeds or bleeding gums

Other general symptoms that may indicate leukemia include:

• Unexplained weight loss
• Swollen lymph nodes, enlarged liver or spleen
• Bone or joint pain
• Night sweats

It is crucial to consult a healthcare professional if any of these symptoms persist, as early diagnosis can significantly impact treatment outcomes.

The classification of leukemia is complex but generally based on two main factors: the speed of disease progression (acute or chronic) and the type of white blood cell affected (myeloid or lymphoid). This categorization helps in understanding the nature of the disease and guiding appropriate treatment strategies. There are four main types of leukemia explained by these distinctions.

Acute vs. Chronic Forms

Leukemia is categorized by its progression rate:

• Acute Leukemia: This form progresses rapidly, involving immature blood cells (blasts). These cells cannot perform their normal functions and multiply quickly, leading to a rapid worsening of symptoms. Acute leukemia requires immediate, aggressive treatment.
• Chronic Leukemia: This form progresses more slowly, involving more mature blood cells. These cells can still perform some of their normal functions for a time. Symptoms may be mild or absent in the early stages, and the disease may be monitored before treatment is initiated.

Myeloid vs. Lymphoid Leukemia

Leukemia is also classified by the type of white blood cell affected:

• Myeloid Leukemia: This type affects myeloid cells, which normally develop into red blood cells, platelets, and certain types of white blood cells (neutrophils, eosinophils, and basophils).
• Lymphoid Leukemia: This type affects lymphoid cells, which normally develop into lymphocytes (T cells and B cells), key components of the immune system.

Combining these classifications yields the four main types of leukemia:

Globally, acute myeloid leukemia (AML) is one of the most common acute leukemias in adults, while acute lymphoblastic leukemia (ALL) is the most common type of cancer in children [Source: American Cancer Society]. Chronic lymphocytic leukemia (CLL) is the most common chronic leukemia in adults.

The leukemia diagnosis process typically begins with a thorough physical examination and a review of the patient’s medical history and symptoms. If leukemia is suspected, a series of specialized tests are performed to confirm the diagnosis, identify the specific type of leukemia, and assess its extent.

Key diagnostic steps include:

• Blood Tests: A complete blood count (CBC) is usually the first step. It measures the number of red blood cells, white blood cells, and platelets. Abnormal results, such as a very high white blood cell count or the presence of immature cells (blasts), can indicate leukemia. A peripheral blood smear is also examined under a microscope to identify abnormal cells.
• Bone Marrow Biopsy and Aspiration: This is a definitive diagnostic procedure. A small sample of bone marrow liquid (aspiration) and solid tissue (biopsy) is taken, usually from the hip bone. These samples are then examined by a pathologist to identify leukemia cells, determine their type, and assess the percentage of blast cells.
• Cytogenetics and Molecular Testing: These tests analyze the chromosomes and genes within the leukemia cells. They can detect specific genetic mutations or chromosomal abnormalities that are characteristic of certain types of leukemia. This information is crucial for prognosis and guiding targeted treatment strategies.
• Lumbar Puncture (Spinal Tap): In some cases, especially with acute leukemias, a lumbar puncture may be performed to check if leukemia cells have spread to the cerebrospinal fluid surrounding the brain and spinal cord.
• Imaging Tests: X-rays, CT scans, or MRI scans may be used to check for enlarged lymph nodes, an enlarged spleen or liver, or other signs of leukemia in different parts of the body.

Accurate diagnosis is paramount for determining the most effective leukemia treatment options.

The selection of leukemia treatment options depends on several factors, including the specific type of leukemia, its stage, the patient’s age, overall health, and personal preferences. Treatment aims to destroy leukemia cells and restore normal blood cell production. Many patients receive a combination of therapies.

• Chemotherapy: This is the most common treatment for many types of leukemia. It involves using powerful drugs to kill cancer cells. Chemotherapy can be administered orally, intravenously, or directly into the cerebrospinal fluid. It often involves multiple drugs given in cycles.
• Radiation Therapy: This treatment uses high-energy X-rays or other particles to kill cancer cells or inhibit their growth. It may be used to target specific areas where leukemia cells have accumulated, such as the brain or spleen, or as a preparation for a stem cell transplant.
• Targeted Therapy: These drugs specifically target vulnerabilities in cancer cells, such as certain proteins or genes that contribute to their growth. For example, tyrosine kinase inhibitors (TKIs) are highly effective in treating chronic myeloid leukemia (CML) by blocking a specific protein that drives cancer cell growth.
• Immunotherapy: This approach uses the body’s own immune system to fight cancer. It can involve various strategies, such as checkpoint inhibitors, CAR T-cell therapy, or monoclonal antibodies, which help the immune system recognize and destroy leukemia cells.
• Stem Cell Transplantation (Bone Marrow Transplant): This intensive treatment replaces diseased bone marrow with healthy blood-forming stem cells. It typically involves high doses of chemotherapy or radiation to destroy existing bone marrow, followed by the infusion of donor stem cells (allogeneic transplant) or the patient’s own previously harvested stem cells (autologous transplant).
• Supportive Care: Throughout treatment, supportive care is crucial. This includes managing side effects, preventing and treating infections, and providing blood transfusions as needed to address anemia or low platelet counts.

The choice of treatment is highly individualized and often involves a multidisciplinary team of specialists.