Leukemia is a type of cancer that starts in the blood cells, usually the bone marrow (the spongy tissue found inside the bones). The blood cells have three types of cells: the white blood cells that acts as an antigen against infection; the red blood cells that helps to circulate oxygen; and the platelets that help blood clots. Leukemia is the overproduction of abnormal white blood cells i.e. the part of the blood cells of the immune system which helps to defend the body against infection.
The white blood cells normally grow and divide itself in an orderly manner as the body grows either as additional stem cells or immature cells that become mature blood cell over time. But in people with leukemia, the bone marrow produces abnormal white blood cells that don’t function properly.
A blood stem cell may become a myeloid stem cell or a lymphoid stem cell.
A myeloid stem cell becomes one of three types of mature blood cells:
A lymphoid stem cell becomes a lymphoblast cell and then one of three types of lymphocytes (white blood cells):
Many types of leukemia exists today, some forms of leukemia are more common in children while other forms of leukemia occur mostly in adults. Globally, the estimated number of people with Leukemia is at 749,565 (with over 300,000 new cases occurring after the 2018 statistics of 437,003 cases at 2.8% of new cancer cases), and mortality rate estimated at 400,021 cases.
How Leukemia Occurs
Leukemia is believed to occur when certain blood cells begin to develop various mutations in the human DNA, although there could be other changes in the blood cells that may contribute to the development of leukemia.
Certain abnormalities cause the cell to grow and divide more rapidly and to continue living when normal cells would die. Over time, these abnormal cells can crowd out healthy blood cells in the bone marrow, leading to fewer healthy white blood cells, red blood cells and platelets, causing the signs and symptoms of leukemia.
Classifications of Leukemia
Leukemia is usually classified into two parts: the first group is relating to how fast it develops and gets worse while the other group is by which type of blood cell is involved.
Leukemia by Development or Progress
Acute Leukemia: Here, most of the abnormal blood cells in the blood stem are usually immature blood cells called blasts; and can’t carry out normal functions required of them. Over time, these immature blood cells develop and multiply rapidly, making the disease grows worse quickly. Acute leukemia requires aggressive and well - timed treatment.
Chronic Leukemia: Chronic leukemia can develop various types of leukemia. Some of this chronic leukemia tends to produce too many cells, causing just a few blood cells to be produced. It usually involves more mature blood cells; reproducing more of these blood cells slowly and functioning normally for a period of time. As it progresses, it tends to get worse than acute leukemia. Also, chronic leukemia initially produces no clinical presentation and can go undiagnosed for a very long time.
Leukemia by White Blood Cells Involved
This group is divided into lymphocytic and myelogenous leukemia
Types of Leukemia
The major types of leukemia are:
There are other types of leukemia which are less common, and they include: