Leukemia: Symptoms, Causes, Types, Diagnosis, Treatment & Prevention

Leukemia definition

Leukemia is a type of cancer that affects the blood and bone marrow, causing the abnormal production of white blood cells. These abnormal white blood cells cannot fight against infection and impair the ability of the bone marrow to produce red blood cells and platelets. Leukemia is acute or chronic. This condition can be characterized by symptoms such as fever, weakness and fatigue, headaches, enlarged liver and spleen, swollen tonsils, bone pain, and weight loss. 

The cause of leukemia is not known, however, factors that put some people at higher risk include exposure to severe radiation, exposure to certain chemicals, such as benzene, and viruses like the Human T-cell leukemia virus. Hematologists and oncologists usually treat and manage leukemia.

Leukemia meaning

The word leukemia comes from the Greek word “leukos”, meaning "white," and “haima”, meaning "blood”.

Leukemia prevalence

Prevalence of Leukemia in the World

In 2020, leukemia accounted for nearly 2.5 percent of all new cancer cases worldwide, with 474,519 new cases identified. The age-standardized incidence rate was 5.4 per 100,000 population, indicating significant geographical variation, with higher rates in North America and lower rates in some areas of Africa.

Prevalence of Leukemia in India

Leukemia is the sixth most common cancer between 1990 and 2019 (apart from other neoplasms), accounting for approximately 6.79% of all cancers. With a 0.78% difference, men are more likely to get leukemia than women. Leukemia is more common in men (7.17%) than in women (6.39%).

Types of leukemia

Leukemia can be chronic (slow growing) or acute (more aggressive), with lymphocytic leukemia starting in lymphoid cells, and myelogenous leukemia starting in myeloid cells. The following are some of the main subtypes of leukemia:

Acute lymphocytic leukemia (ALL)

Also called acute lymphoblastic leukemia. It is the most common type of leukemia. Typically, it occurs in young children but can also affect adults. It originates from bone marrow lymphoid cells. It rapidly spreads to other body parts, like the central nervous system (brain and spinal cord), liver, lymph nodes, spleen, and testicles in male patients.

Acute myelogenous leukemia (AML)

Also called acute granulocytic leukemia, acute myelocytic leukemia or acute myelogenous leukemia, acute myeloid leukemia, or acute non-lymphocytic leukemia. It is the most common type of leukemia in adults and also affects children. Originating from bone marrow myeloid cells and rapidly spreads the central nervous system (brain and spinal cord), liver, lymph nodes, spleen, and testicle in male patients.

Chronic myelogenous leukemia (CML)

Also called chronic myeloid leukemia. And typically affects adults. It is a slow-developing condition originating from bone marrow myeloid cells, which can take months or years to spread to blood and other body parts.

Chronic lymphocytic leukemia (CLL)

This type of leukemia develops slowly. It typically affects older adults. It originates from bone marrow lymphoid cells and may initially remain asymptomatic for years before symptoms appear or treatment is sought. It can eventually enter the bloodstream and spread to other parts of the body.

Other subtypes:

Chronic myelomonocytic leukemia (CMML):

It is a condition that originates in bone marrow myeloid cells and typically affects older adults, potentially causing bloodstream infections. An enlarged spleen, shortage of some types of blood cells, and more monocytes (white blood cells) occur in people with CMML.

Hairy cell leukemia (HCL)

It is a rare type of chronic leukemia originating from bone marrow, characterized by short, hair-like projections on the cancerous cells.

Juvenile myelomonocytic leukemia (JMML)

Also called Juvenile chronic or myeloid leukemia (CMML) of childhood, it is a rare blood cancer, and it is most common in infants and children under 4 years of age accounting for 1-2 percent of all childhood leukemia. It is more prevalent in males, according to WHO (World Health Organization).

Large granular lymphocytic leukemia (LGLL)

It is a type of chronic leukemia that affects white blood cells called "lymphocytes". which is part of the immune system and helps fight certain infections. It has two types: T-cell (T-LGL) and natural killer cell (NK-LGL), which can be either chronic (slow-growing) or aggressive (fast-growing) and it affects men and women typically at the age of 60 years. 

Blastic plasmacytoid dendritic cell neoplasm (BPDCN)

Also called natural killer (NK) cell leukemia. This type was first recognized by WHO (World Health Organization) in 2008. It is a rare cancer that often combines characteristics of lymphoma and leukemia. It has limited data and no established treatment, with an average diagnosis age of 60-70 years, and it affects men twice as frequently as it does women.

B-cell prolymphocytic leukemia (B-PLL)

It is a rare disease, an aggressive disease affecting older adults, at the age of 69 years. It's slightly more common in men and often develops from slow-growing B-cell cancers like chronic lymphocytic leukemia.

T-cell prolymphocytic leukemia (T-PLL)

It is a rare disease, aggressive form of cancer characterized by the uncontrolled growth of mature T-cells, it affects white blood cells that protect the body from infection. It affects older adults, with an age of 61 years, and it frequently affects men.

Leukemia symptoms

Patients with chronic leukemia may not have any symptoms, and their condition is usually identified through usual blood tests. However, for people with acute leukemia, or when the disease progresses, signs and symptoms may include:

• Fever 
• Fatigue and weakness
• Anemia 
• Loss of appetite 
• Swollen lymph nodes, enlarged liver or spleen
• Easy bleeding or bruising or tiny red spots in the skin (petechiae)
• Shortness of breath (SOB)
• Unexplained weight loss
• Bone pain 
• Frequent infections
• Dizziness
• Headaches
• Abdominal pain (stomach pain)
  

Leukemia causes and risk factors

The exact cause of leukemia is not known, but there are several risk factors that may increase the chance of developing the disease. Below are some of the risk factors for leukemia: 

• Age: Most types of leukemia, particularly chronic leukemias, become increasingly prevalent as people age. However, acute lymphocytic leukemia (ALL) is more common in children than adults.

• Gender: The majority of leukemia types are slightly more prevalent in males than in females.

• Tobacco smoking: Cigarettes contain numerous cancer-causing substances. According to researchers, smoking accounts for approximately 20% of all acute myelogenous leukemia (AML) cases.

• Family history: People who have a first-degree relative with chronic lymphocytic leukemia (CLL), such as a parent, child, or sibling, are two to four times more likely to develop CLL. The majority of people who develop leukemia do not have a family history of the disease.

• History of radiation therapy or chemotherapy: Radiation therapy and chemotherapy may result in mutations, or alterations in a cell's DNA, which can lead to malignancies like leukemia. AML is associated with therapies for Hodgkin's lymphoma, non-Hodgkin lymphoma, childhood ALL, and other cancers such as breast and ovarian cancer.

• Exposure to cancer-causing agents: People who have been exposed to high doses of radiation (from an atomic bomb explosion, working in atomic weapons production, or being involved in a nuclear reactor disaster) are more likely to develop leukemia. Long-term exposure to high quantities of solvents, such as benzene, is a known risk factor, particularly in the workplace. CLL may also be associated with exposure to Agent Orange, a chemical commonly employed during the Vietnam War.

• Rare genetic syndromes: Individuals with Down syndrome, Fanconi anemia, ataxia-telangiectasia, and Bloom syndrome have a slightly increased chance of acquiring leukemia.

• Myelodysplastic syndromes: Approximately one-third of patients with this bone marrow failure disease develop leukemia.

• Blood disorders: People with certain blood conditions are more likely to develop acute myelogenous leukemia (AML). These disorders include myelodysplastic syndromes.
  

Complications of leukemia

Patients with leukemia are highly affected by anemia, infections, and bleeding that are linked to the disease. Below are some of the complications of leukemia: 

• Tumor Lysis Syndrome (TLS): Tumor cells die rapidly, releasing intracellular content into the bloodstream, causing high serum potassium, phosphorus, and uric acid levels. Patients need aggressive hydration, frequent monitoring, and hyperuricemia management.

• Disseminated Intravascular Coagulation (DIC): Dysfunctioning proteins in blood clotting proteins lead to thrombosis and hemorrhage associated with acute promyelocytic leukemia but can occur in other leukemia subtypes. Monitoring the active replacement of fibrinogen with cryoprecipitate is crucial for patient survival.

• Infection: Leukaemia increases the risk of infection due to immunosuppression from chemotherapy, and stem cell transplantation. Immunosuppressed patients with fever must immediately be evaluated and need to start broad spectrum antibiotic therapy.

• Cancer: Survivors of leukemia have an increased chance of developing future malignancies. For example, the Childhood Cancer Survivor Study found that the 30-year cumulative incidence of any cancer after leukemia was 5.6%, with a median delay to the onset of the second disease of nine years. The most prevalent secondary neoplasms in childhood leukemia survivors are distinct subtypes of leukemia or lymphoma.
  

Leukemia diagnosis

Early diagnosis and treatment of leukemia are necessary to prevent the progression of leukemia. To determine the type of leukemia, oncologists develop a definitive diagnosis. The following are the steps involved in diagnosing leukemia: 

• Initial evaluation
• Medical history
• Physical examination 
• Laboratory testing
• Complete blood count (CBC)
• Liver function tests (LFTs) 
• Comprehensive metabolic panel
• Coagulation panel
• Urea and electrolytes
• Peripheral Blood Smear
• Biopsy techniques
• Bone marrow biopsy and aspiration 
• Lymph node biopsy
• Imaging tests
• Computed tomography (CT)
• Magnetic resonance imaging (MRI) 
• positron emission tomography (PET)
• Chest X-ray
• Ultrasound 
• Biomarker Testing
• Immunophenotyping
• Cytogenetics
• Flow Cytometry
• Fluorescence In Situ Hybridization (FISH)
• Lumbar puncture
  

Leukemia treatment

Leukemia cancer is usually treatable when it is diagnosed early, and the treatment depends on the type & size of the cancer, how far it has spread, and the general health of the patient. Treatment options includes surgery, chemotherapy, radiotherapy, and targeted drug therapy may also be included.

The treatment of leukemia includes the following:

• Chemotherapy
• Other drug therapies
• Stem cell transplant
• Radiation therapy
• Targeted therapy
• Immunotherapy

Clinical trials are undergoing for new treatments, and it may be necessary to provide follow-up care.

Leukemia prevention

Because the cause of leukemia is uncertain, there is no definitive strategy to prevent it. However, it is typically recommended to avoid solvents such as benzene and toluene, as well as unnecessary x-ray exposure. If patients suspect they have leukemia, knowing the risk factors and symptoms, as well as discussing them with doctor, are crucial for early diagnosis and treatment. People with a family history of leukemia should be particularly mindful of signs and share their medical history with their doctor.

Difference between Leukemia and Lymphoma

Leukemia vs lymphoma

Both leukemia and lymphoma are cancers of the blood, bone marrow or lymph (a clear fluid that circulates white blood cells throughout the body), but they have some key differences. The following are the parameters that differentiate leukemia and lymphoma: