What Is Leukemia? Causes, Types & Key Facts

Leukemia Definition: Leukemia, also known as Leukemia, is a category of blood cancers that typically start in the bone marrow and result in a large number of irregular blood cells. These blood cells, also known as blasts or Leukemia cells, are not completely formed.

What is the Meaning of Leukemia?

There is no major difference between Leukemia definition and Leukemia meaning. To explain the meaning of Leukemia in an elaborate manner, it is cancer that begins in blood-forming tissue, most often in the bone marrow. It causes an overabundance of dysfunctional white blood cells, which are part of the immune system's defence against infection.

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Leukemia Classification

Leukemia is classified into many broad categories based on clinical and pathological characteristics. The first distinction is between acute and chronic forms of the disease:

1. Acute Leukemia: 

It is described by a rise in the number of immature blood cells in a short period of time. Because of the overcrowding caused by these cells, the bone marrow is unable to generate healthy blood cells, resulting in low haemoglobin and platelets. Because of the rapid progression and accumulation of malignant cells, which then spill over into the bloodstream and spread to other organs of the body, acute Leukemia requires immediate care. The most common form of Leukemia in children is acute Leukemia.

2. Chronic Leukemia: 

Chronic leukemia is described by an irregular accumulation of white blood cells that are relatively mature but still abnormal. The cells are formed at a much higher rate than average, resulting in many irregular white blood cells, which can take months or years to progress. Unlike acute Leukemia, which must be treated right away, chronic Leukemia is often tracked for a period of time before treatment to ensure that the medication is as successful as possible. Chronic Leukemia is more common in older people, but it can strike anyone at any age.

In addition, diseases are classified based on the type of blood cell that is affected. This distinguishes between lymphoblastic and lymphocytic leukemias, as well as myeloid and myelogenous leukemias:

3. Lymphocytic Leukemias: 

The cancerous shift in lymphoblastic or lymphocytic leukemias occurs in a type of marrow cell that usually forms lymphocytes, which are infection-fighting immune system cells. A particular subtype of lymphocyte, the B cell, is involved in the majority of lymphocytic leukemias.

4. Myelogenous Leukemias: 

The cancerous shift in myeloid or myelogenous leukemias occurs in a type of marrow cell that usually forms red blood cells, several other types of white cells, and platelets.

Pre-Leukemia Meaning

The irregular proliferation of a clone of non-cancerous megakaryoblasts causes transient myeloproliferative disease, also known as transient Leukemia. The disorder is only seen in people who have Down syndrome or genetic abnormalities that are similar to Down syndrome. It occurs in a baby during pregnancy or shortly after birth, resolves within 3 months, or progresses to acute megakaryoblastic Leukemia in 10% of cases. Transient myeloid Leukemia is a form of pre-leukemia.

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Characteristics of Leukemia

Signs and Symptoms

• Simple bruising, pale skin, fever, and an enlarged spleen or liver are the most common symptoms in children.

• Damage to the bone marrow causes a shortage of blood platelets, which are vital in the clotting process, by displacing normal bone marrow cells with higher numbers of immature white blood cells. This means that people with Leukemia are more likely to bruise quickly, bleed profusely, or develop pinprick bleeds (petechiae).

• White blood cells, which help combat infections, may be suppressed or defective. This could make the person's immune system incapable of fighting off a simple infection, or it could cause the immune system to destroy other body cells.

• Since Leukemia impairs the immune system's ability to function normally, some people develop infections on a regular basis, which may range from swollen tonsils, mouth sores, or diarrhoea to life-threatening pneumonia or opportunistic infections.

• Finally, a lack of red blood cells causes anaemia, which may cause dyspnea and pallor.

• Many flu-like symptoms include feeling sick, developing fevers, chills, night sweats, being tired, and other flu-like symptoms. Owing to an enlarged liver and spleen, some people experience nausea or a sensation of fullness, which can lead to unintentional weight loss. Blasts affected by the disease can clump together and swell in the liver or lymph nodes, resulting in pain and nausea.

• If leukemic cells infiltrate the central nervous system, neurological symptoms (particularly headaches) can develop. Brain stem pressure can cause unusual neurological symptoms such as migraines, seizures, or coma.

Causes

Any of the various forms of leukemias have no single identifiable cause. Just a few cases are attributed to the few identified triggers, which are not necessarily factors beyond the control of the average individual. The majority of Leukemia cases have no clear cause. The causes of different leukemias are likely to be different.

Leukemia, like other cancers, is caused by DNA mutations. By activating oncogenes or deactivating tumour suppressor genes, some mutations may trigger Leukemia by disrupting the regulation of cell death, differentiation, and division. These mutations may happen naturally or as a result of radiation or carcinogenic substances exposure.

Natural and artificial ionising radiation, a few viruses, such as the human T-lymphotropic virus, and some chemicals, especially benzene and alkylating chemotherapy agents for previous malignancies, are all known causes in adults. 

Tobacco use in adults is linked to a modest rise in the risk of developing acute myeloid Leukemia. Some petrochemicals and hair dyes have been related to the development of Leukemia in cohort and case-control studies. While eating more vegetables can confer a small protective benefit, the diet has a very limited or no effect.

Viruses have also been related to Leukemia in some cases. The human T-lymphotropic virus (HTLV-1) causes adult T-cell lymphoma.

Diagnosis of Leukemia

Following reports of the symptoms, a diagnosis is normally made based on repeated full blood counts and a bone marrow test. Blood tests may fail to detect Leukemia in some cases, especially in the early stages of the disease or during remission. In certain cases, a lymph node biopsy may be used to diagnose some forms of Leukemia.

Blood chemistry tests can be used after a diagnosis to assess the extent of liver and kidney damage, as well as the effects of chemotherapy on the patient. Doctors can use an X-ray, MRI, or ultrasound if they are concerned about other leukemia-related damages.

These can reveal leukemia's effects on bones (X-ray), the brain (MRI), or the kidneys, spleen, and liver (liver biopsy) (ultrasound). Though it is rare, CT scans may be used to check lymph nodes in the chest.

Many individuals have not been diagnosed with Leukemia through the use of these methods to determine whether or not they have the disease because many of the signs are unclear, non-specific, and may refer to other illnesses. As a result, according to the American Cancer Society, at least one-fifth of people with Leukemia have yet to be diagnosed.

Treatment of Leukemia

Leukemia is treated using a variety of medical methods. The type of Leukemia, the patient's age and health status, and whether or not the Leukemia cells have spread to the cerebrospinal fluid will all influence treatment. The type of treatment that is most suitable depends on the genetic changes or particular characteristics of the Leukemia cells as determined in the laboratory.

Chemotherapy (the most common treatment for Leukemia), radiation therapy, biological therapy, targeted therapy, and stem cell transplant are all options for Leukemia treatment. These therapies can be used in combination. If the spleen is swollen, it can be surgically removed as part of the treatment.

Acute Leukemia must be treated with the intention of achieving remission (absence of Leukemia cells in the body). After achieving remission, medication may be used to prevent leukemia from relapsing. Consolidation of maintenance therapy is the term for this. Treatment for acute leukemias may also result in a cure.

Treatments for chronic leukemias are unlikely to cure the disease, although they can also suppress cancer and manage symptoms. Some people with chronic Leukemia may be eligible for stem cell transplantation, which has the potential to cure them.

Before starting care for Leukemia, several patients seek a second opinion. In most cases, there is enough time to seek a second opinion and consider treatment alternatives without jeopardising the effectiveness of the current treatment. Treatment must, however, be started right away in rare cases of extremely aggressive leukemias. A doctor should be consulted about the prospect of seeking a second opinion as well as any possible treatment delays. The majority of physicians support the opportunity for a second opinion and should not be insulted if a patient requests one.

1. Chemotherapy:

Chemotherapy is the use of drugs to destroy rapidly dividing cells, such as those found in Leukemia and other cancers. Chemotherapy may be taken orally as a pill or tablet, or it can be injected directly into the bloodstream through a catheter or intravenous line. Combination chemotherapy, which entails the use of more than one drug, is commonly used. The medications are administered in stages with breaks in between.

Chemotherapy side effects vary depending on the medications used and the dose or regimen used. Hair loss, nausea, vomiting, mouth sores, loss of appetite, tiredness, quick swelling or bleeding, and an increased risk of infection due to the breakdown of white blood cells are some of the side effects of chemotherapy drugs. Chemotherapy side effects can be managed with the use of medications.

2. Biological Therapy:

Biological therapy is any cancer treatment that uses living organisms, living organism-derived drugs, or synthetic forms of these substances. These therapies assist the immune system in recognising and attacking defective cells. Antibodies, tumour vaccines, and cytokines are examples of biological treatments for different forms of cancer (substances that are produced within the body to control the immune system).

Biological therapies have fewer side effects than chemotherapy, which can include a rash or swelling at the injection site for IV infusions of therapeutic agents. Headache, body aches, fever, and tiredness are some of the other possible side effects.

3. Targeted Therapy:

Instead of killing all rapidly growing cells indiscriminately, targeted therapies interfere with one particular property or function of a cancer cell. This means that targeted therapy does less damage to normal cells than chemotherapy. Targeted therapies can cause the target cell to stop growing rather than die, and they can stop cancer cells from spreading by interfering with specific molecules that promote cancer development. Cancer treatments that are molecularly targeted are also known as precision medicines, molecularly targeted drugs, or molecularly targeted therapies.

Targeted drugs are administered as pills or injections. Swelling, bloating, and weight gain are also possible side effects. Nausea, vomiting, diarrhoea, muscle cramps, and rash are some of the other possible side effects.

4. Radiation Therapy:

High-energy radiation is used to target cancer cells in radiation therapy. Radiation therapy can be used to treat leukemia that has spread to the brain, as well as the spleen and other organs where leukemia cells have accumulated.

Radiation therapy has side effects as well, although they are unlikely to last. The position of the body that is irradiated determines the side effects. Radiation to the abdomen, for example, can cause nausea, vomiting, and diarrhoea. The skin in the treated area can become red, dry, and tender as a result of radiation therapy. While undergoing radiation therapy, generalised tiredness is also normal.

5. Stem Cell Transplant:

High doses of chemotherapy and/or radiation are used in stem cell transplantation to destroy leukemia cells as well as normal bone marrow. Transplant stem cells are then administered via intravenous infusion. The stem cells make their way to the bone marrow, where they begin to produce new blood cells. The patient's own stem cells or those from a donor may be used.