Leukemia

Leukemia refers to a group of blood disorders that involves the excessive number of white blood cells - both mature and immature - that circulate throughout the body and for this reason, leukemia is considered a part of the so-called 'hematological neoplasms.

The incidence of leukemia is lower in the African-Americans than in Caucasians and children of Jewish families have a higher incidence than the non-Jewish children. Chronic lymphocytic leukemia is rarer in the South Asian countries compared to the Western countries where acute leukemia forms a major chunk (between 42 and 68 %) of all cancer cases. It has been found that acute leukemia is the disease in almost all the cases and almost 68% of the cases are below 6 years of age. In cases of chronic leukemia, 80% cases occur in people above 50 years of age and about 4% in patients below 14 years of age.

Leukemia

Research throws up four strong contenders for the possible cause of leukemia:

(a) Ionizing radiation - mostly of artificial origin

(b) Some chemicals -specifically benzene

(c) Certain viruses

(d) Genetic vulnerability

One of the major causes of leukemia is mutations caused by exposure to ionizing radiation, mainly from artificial sources, as they produce higher fluxes. This exposure to radiation as well as some chemicals disrupt the process of cell division, differentiation and cell death leading to leukemia.

Some forms of leukemia are directly attributable to infection by the human immunodeficiency virus (HIV) or the human T-lymphotropic virus (HTLV-1 and /or HTLV-2).

Leukemia can be divided on the basis of the type of cell, that is, lymphocytic leukemia (which arises from a type of white blood cells called lymphocytes) or myeloid leukemia (caused by an a type of immature white blood cell called a myeloid stem cell). It can also be divided on the basis of speed of growing, that is, the faster variety called acute leukemia and the slower growing variety called the chronic. The combinations of these types gives rise to four groups of leukemia:

(a) Acute lymphocytic leukemia

(b) Chronic lymphocytic leukemia

(c) Acute myeloid leukemia

(d) Chronic myeloid leukemia

In chronic leukemia, the number of relatively mature but abnormal white cells in the blood goes up while in acute leukemia, immature white blood cells accumulate in the bone marrow and prevent it from producing healthy white blood cells.