Causes of Leukemia
Although researchers have studied the many cellular changes associated with leukemia, it is unknown why these changes occur. It is likely that certain risk factors are involved. Many factors (e.g., age, genetics) are unmodifiable (beyond control). Other factors (e.g., environmental, lifestyle-related variables) are more controllable (modifiable).
It is now known that all cancers, including leukemia, begin as a mutation in the genetic material—the DNA (deoxyribonucleic acid)—within certain cells. The external or internal causes of such change probably add up over a lifetime. Leukemia begins when one or more white blood cells experience DNA loss or damage. Those errors are copied and passed on to subsequent generations of cells. The abnormal leukemic cells remain in an immature blast form that never matures properly. They do not die off like normal cells, but tend to multiply and accumulate within the body.
DNA errors also may occur in the form of translocations—damage produced when part of one chromosome becomes displaced and attached to another chromosome. Translocations disrupt the normal sequencing of the genes. As a result, oncogenes (cancer-promoting genes) on the chromosomes may be "switched on," while tumor suppressors (cancer-preventing genes) may be switched off. Many leukemias contain translocations that affect the blood cell chromosomes. Physicians often test for these translocations to help diagnose leukemia, determine a patient's prognosis, and identify cancer recurrence.