When a cancerous mutation is formed in blood cell-forming tissue, bone marrow, leukemia is the result. Leukemia is the most common type of childhood cancer which causes mutations to white blood cells. Leukemia cells also do not die when they should (when they are old or damaged), as the other blood cells do so the mutated white blood cells crowd out the healthy blood cells. Without normally functioning white blood cells, the body has difficulties transporting oxygen to the tissues, controlling blood loss, and fighting infections. Over time, the leukemia can spread from the bone marrow to other organs.
In 2013, the estimated new cases of leukimia were 48,610 and the estimated deaths from leukemia were 23,720 (http://www.cancer.gov/cancertopics/types/leukemia). As these numbers indicate, a substantial number of individuals are affected by leukemia alone. Leukemia is a broad term for blood cancer, however, and can be further broken down into categories.
The categories of leukemia fall into two broad groups: acute and chronic. Acute leukemia tends to develop faster than chronic leukemia. The acute leukemia cells do not work like normal white blood cells, while the chronic leukemia cells function nearly as well as the normal cells. These differences lead to acute leukemia causing individuals to be very tired, bruise more easily, and get infections more readily, while people with chronic leukemia start off feeling normal, and then may progress into experiencing similar symptoms as those who have acute leukemia.
In these two broad groups, there are several types of leukemia. The four most common types are acute myeloid leukemia (AML), acute lymphoblastic leukemia (ALL), chronic myeloid leukemia (CML), and chronic lymphocytic leukemia (CLL). Chemotherapy, targeted therapy, radiation therapy, and stem cell transplant are some examples on how leukemia is treated, depending on the type of leukemia and the age and health of the patient.
Symptoms of Leukemia
The Human Genome Project and Cancer 