26. Leukemia
Leukemia refers to a group of cancers in which the malignant cells circulate in the bloodstream: the word “leukemia” derives from the joining of two Greek terms, leukos, or “white,” and -emia, meaning “of theblood.”
Because blood cells are created in the bone marrow, the marrow is always involved in cases of leukemia. There have been tremendous advances in our understanding of the scientific basis of leukemia.
Thousands of genetic changes that are critical to leukemia development have been documented, and probably more is known about the science of leukemia than about any other cancer. This knowledge has recently begun to pay off in dramatic improvements in treatment, especially for chronic myelogenous leukemia.
I have found that when a person is first referred to me with an abnormal blood count, the disease he or she fears most is leukemia. This is because most people think of leukemia as being a rapidly fatal disease.
The truth is that although some types of leukemia can indeed be rapidly fatal if not treated successfully, others may not need to be treated for twenty years or more.
There are four main types of leukemia: acute myelogenous leukemia (AML), acute lymphoblastic leukemia (ALL), chronic myelogenous leukemia (CML), and chronic lymphocytic leukemia (CLL). Acute leukemias (AML and ALL) usually need to be treated soon after diagnosis, whereas chronic leukemias usually do not need urgent treatment because they grow more slowly, often do not cause symptoms, and may remain stable without therapy for months or, in the case of CLL, several years. Leukemia can be treated with chemotherapy, more specific targeted therapies, stem cell transplantation, or a combination of these approaches.
Space limitations prevent a discussion of each type, so I focus here on CML, a disease that has become the model for the future treatment of all cancers, and on CLL, the most common type of leukemia.
