Leukemia means cancer of blood-forming tissues, which leads to the production of a high number of abnormal blood cells, especially white blood cells (WBCs). To understand leukemia, we need to know more about the different types of blood-forming tissues and blood cells.
The blood-forming tissues
Our body contains a factory called bone marrow, which forms blood cells. The bone marrow is a soft tissue located inside some bones, such as the hip bone, skull bones, ribs, and vertebrae. It forms the three types of blood cells: red blood cells (RBCs), white blood cells (WBCs), and platelets. These cells arise from stem cells (hematopoietic stem cells) that divide to form two types of immature cells: myeloid stem cells (myeloblasts) and lymphoid stem cells (lymphoblasts). These cells grow to be the mature blood cells; myeloblasts give red blood cells, some types of white blood cells (neutrophils, eosinophils, basophils, and monocytes), and platelets while lymphoblasts give lymphocytes.
The bone marrow produces blood cells according to the body’s needs. All of these cells have a life span, after which they die, and the bone marrow produces new cells. Under certain circumstances, the bone marrow produces the cells at a higher rate. For example, it creates more red blood cells in hypoxia and anemia, more white blood cells in infection, and more platelets in bleeding.
In leukemia, there is an abnormal and uncontrolled increase in the production of immature blast cells unable to do the function of mature cells. In most cases, these increased immature cells are immature white blood cells, but it may occur in other blood cells.