Leukemias are characterized by abnormal and excessive proliferation of blood cell precursors, in particular precursors of the white blood cell subsets, in the bone marrow then blood.
These diseases are clinically and biologically highly heterogeneous and are subdivided into two main groups according to whether they originate from lymphoid or myeloid tumor cells.
Among these two categories, the leukemias are classified in:
- Chronic Leukemia (slow evolution of already differentiated mature cells),
- Acute Leukemia (fairly rapid clinical evolution, associated with the proliferation of young cells blocked at an early stage of their differentiation).
Leukemias are characterized by relative simple genetic anomalies, which analysis is facilitated by an easy access to the diseased cells, i.e. bone marrow and blood sampling.
Leukemia diagnosis is based on:
- Marrow and blood microscopic analysis,
- Chromosomal study (cytogenetics),
- Identification of disease-specific rearranged genes (molecular diagnostics),
- Characterization of cell surface marker proteins (flow cytometry).
The last three analysis allow to specifically identifying the leukemia subtypes.
Available therapeutic approaches widely differ according to any given type of leukemia:
- Chemotherapy, substituting normal cells to the marrow's cancerous cells,
- Bone marrow grafts, following intensive chemotherapy and radiation treatment, allowing normal blood system recovery and facilitating the removal of residual cancerous cells thanks to the grafted white blood cells,
- Targeted therapies:
- All-transretinoic acid (ATRA) derivatives, allowing the transformation of the cancerous cells in normal cells in the PML-RARa leukemia subset,
- Glivec® for the treatment chronic myeloid leukemia.
In the last thirty years, leukemia patient care significantly advanced and, in turn, helped improving prognosis of some leukemias. For instance, lymphoblastic children leukemia death rates significantly dropped allowing close to 80% recovery.
This advance would not have been possible without the contribution of research, new targeted drugs development and better diagnosis.
