Leukemias are hematological malignancies involving white blood cells.There are several types of leukemia, divided based on whether the disease is acute or chronic and whether it starts in myeloid cells or lymphoid cells .
What is Leukemia?
Leukemia is a malignant, progressive, hematological disease in which the bone marrow and other blood-forming organs produce increased numbers of immature or abnormal leukocytes (white blood cells). These immature (early forming) and abnormal blood cells suppress the production of normal (healthy) blood cells, leading to anemia and other symptoms.
Under normal circumstances, healthy cells form in the bone marrow where they mature into red blood cells (the delivery of oxygen and nutrients to cells in the body), white blood cells (to fight infections) and platelets (to stop bleeding). However, in patients diagnosed with leukemia, these cells do not mature as they should or they transform into irregular blood cells that do not function normally.
When these abnormal cells build up in the bone marrow and bloodstream, patients may experience anemia, become susceptibility to infections and bleeding that does not clot due to the lack of functional red blood cells, white blood cells and/or platelets.
Signs & Symptoms
Patients diagnosed with leukemia are at significantly increased risk for developing infections, anemia, and bleeding. Other symptoms and signs may include easy bruising, weight loss, night sweats, and unexplained fevers.
Acute leukemia is characterized by a rapid increase in the number of immature and abnormal blood cells. Acute leukemia requires immediate treatment because of the rapid progression and accumulation of the malignant cells. As a result of this rapidly increasing level of immature and abnormal blood cells, the bone marrow is unable to produce healthy blood cells resulting in low hemoglobin and low platelets.
Acute forms of leukemia are the most common forms of leukemia in children and teens, accounting for approximately 1 out of 3 cancers.
In contrast to acute leukemia, chronic leukemia is characterized by the excessive buildup of relatively mature , but still abnormal, white blood cells.
Chronic leukemia typically taking months or years to progress. The disease results in many abnormal white blood cells because cells are produced at a much higher rate than normal, healthy, cells.
Also, in contrast to acute leukemia, which requires immediate treatment, chronic leukemia can be monitored for some time before treatment to ensure maximum effectiveness of therapy.
Lymphoblastic or lymphocytic leukemias
Leukemia is subdivided according to the kind of blood cell is affected - lymphoblastic or lymphocytic leukemias and myeloid or myelogenous leukemias.
In lymphoblastic or lymphocytic leukemias, the cancerous change takes place in a type of marrow cell that normally goes on to form lymphocytes, infection-fighting immune system cells.
Most lymphocytic leukemias involve a specific subtype of lymphocyte, B cell.
In myeloid or myelogenous leukemias, the cancerous change takes place in a type of marrow cell that normally goes on to form red blood cells, some other types of white cells, and platelets.
According to data from the National Cancer er In institute , an estimated 60,530 people will be diagnosed with a form of leukemia in 2020. This represents 3.4% of all new diagnosed cancers in this year. The same statistics estimate that 23,100 people will die of leukemia in 2020 (3.8% of all cancer deaths).
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Classification and Sub-types
Clinically and pathologically, leukemia is classified by the types of cells affected (myeloid or lymphoid) and whether it is fast- or slow-growing (acute or chronic) subdividing the disease in four large groups. These four major sub-types include:
- Acute myeloid leukemia (AML)
- Acute lymphocytic leukemia (ALL)
- Chronic myeloid leukemia (CML)
- Chronic lymphocytic leukemia (CLL)
Some people have a higher risk of leukemia because of a genetic disorder or because they were previously treated with certain chemotherapy drugs or radiation. Although these people have a greater than in the general population, the risk is still relatively low.
Down syndrome (trisomy 21)
Children with Down syndrome are more likely to develop either acute lymphocytic leukemia (ALL) or acute myeloid leukemia (AML). Down syndrome has also been linked with transient leukemia or transient myeloproliferative disorder.
Another genetic disorder linked to a higher risk of developing several kinds of cancer, including leukemia, bone or soft tissue sarcomas, breast cancer, adrenal gland cancer, and brain tumors., is Li-Fraumeni syndrome. Li-Fraumeni syndrome is a rare inherited condition caused by a change in the TP53 gene. A number of other genetic disorders carry an increased risk of leukemia, as well as some other types of cancers including neurofibromatosis and Fanconi anemia.
Early Detection and Diagnosis
Not all forms of leukemia show obvious symptoms early in the disease. As a result, leukemia may be diagnosed incidentally during a physical exam or as a result of routine blood testing.
Signs & Symptoms
Potential signs & symptoms of leukemia may include a patient who appears pale, has enlarged lymph nodes (primarily in the neck, armpits, or groin), swollen gums, an enlarged liver or spleen, significant bruising, bleeding, fever, persistent infections, fatigue, or a small pinpoint rash.
A blood test showing an abnormal white cell count may confirm a diagnosis. To confirm this diagnosis and identify a specific type of leukemia, a needle biopsy and aspiration of bone marrow from a pelvic bone need to be done to further confirm the occurrence of leukemic cells, as well as DNA markers, and chromosome changes in bone marrow.