Chronic leukemia is an incurable chronic disease which progresses through periods of dormancy. This lecture explains  the nature  of cancer dormancy  and  why chronic leukemia is incurable.

Leukemia proceeds through the following phases:
1. Pre-clinical, when leukemia is hidden.
2. Clinical compensated
3. Clinical decompensated, known as blastic crisis.
The first two phases, are asymptomatic and patient feels healthy.
During its compensated phase WBC  count rises from one homeostatic level to the other
Chronic leukemia starts with a transformation of its stem cell whose progeny inherit its phenotype.
CML  stem cell resists any therapy. Nevertheless during its compensation phase CML  evolves in an orderly fashion. WBC count rises in steps during which it maintains homeostasis.

Homeostat is a process in the body which maintains homeostasis.
CML is a homeostat which  controls a WBC count. It has three properties:
1. A set point determined by a special sensor.
2. Maintains a constant WBC level.
3. Following perturbation, the variable returns to its pre-perturbation level.

Since CML is incurable, the only therapeutic option  is to induce and prolong dormancy.
Chronic leukemia is a cancer prototype. Each tumor has its own homeostat called tumorstat. Cancer is an incurable chronic stem cell disease