When abnormal white blood cells are produced excessively the condition results in leukemia. It affects around forty-five thousand people in the country every year. It is the most common form of blood cancer diagnosed in individuals above the age of fifty-five. It is also commonly found among children who are below the age of fifteen. Leukemia develops when abnormal white blood cells in the bone marrow rapidly increase and begin to destroy the normal blood cells. This makes a person vulnerable to infections.

The type of treatment for leukemia depends on the type of white blood cells affected and the severity of the disease (whether it is chronic or acute). There are two main types of leukemia: acute and chronic leukemia. Acute leukemia progresses quickly and is severe. Chronic leukemia, on the other hand, is rather slow. Four common forms of leukemia include:

1. Acute lymphocytic leukemia
This type is commonly found among children. It starts in immature T or B lymphocytes. The immune system is made up of lymphoid tissues for which the lymphocytes are the building blocks. Acute lymphocytic leukemia can also affect the bone marrow of the entire body. This type of leukemia can spread to the spleen, liver, and lymph nodes. Doctors further subcategorized acute lymphocytic leukemia based on the stage of development of the involved lymphocyte.

2. Acute myeloid leukemia
Acute myeloid leukemia is one of the most common forms of leukemia. It is mostly diagnosed among adults and progresses rapidly. Any component of the blood can be affected by this type of leukemia. In the bone marrow, blood stem cells form into either myeloid cells, which can turn into platelets, red blood cells, white blood cells, or lymphoid cells. In this type of leukemia, myeloid stem cells mostly mature into white blood cells or myeloblasts that are mature. But, there are times when they turn out to become platelets or red blood cells. As they start multiplying, they overpower healthy cells in the blood and bone marrow. The cancer cells can also spread to other organs.

3. Chronic lymphocytic leukemia
Chronic lymphocytic leukemia comprises about one-third of the leukemia cases reported and is mostly seen in older adults. One form of this type of leukemia advances gradually. Sometimes, the symptoms may not appear for years. Another type of chronic lymphocytic leukemia progresses rapidly. In this, the cancer begins in B lymphocytes. When the abnormal cells proliferate, they overcrowd the normal cells. There are other subtypes of chronic lymphocytic leukemia which exist that can affect the other types of cells.

4. Chronic myeloid leukemia
This is a rare type of leukemia comprising ten percent of the total diagnosed cases. Adults are more prone to this condition than children. This type of leukemia develops when the genetics begin to change immature myeloid cells into cancer cells. Such cells grow slowly and overpower the healthy cells in the blood and bone marrow. The subtype of this leukemia is difficult to treat.