The leucosis or leukemia is a cancer affecting blood cells also called tumor liquid, as distinct from lymphoma who are also tumors of blood cells but growing in secondary lymphoid areas. In the nineteenth century, the term referred not only deadly disease. The extract blood of patients with this disease was whitish appearance. There are now many types of leukemia, which each require a specific treatment.
In 1847, Rudolf Virchow, a German doctor histologist, was one of the first to describe leukemia. The disease begins in the bone marrow. The leukemia cells behave abnormally due to a change in their genome with an accumulation, the level of their DNA, acquired mutations that allow the transformation of the cell.
Stem cells from bone marrow produce daily billions of red blood cells, white blood cells and platelets.
The leukemia is characterized by an abnormal and excessive proliferation of white blood cell precursors, blocked at a stage of differentiation, which eventually completely invade the bone marrow and blood. Moves then a bone marrow failure with insufficient production of red blood cells (anemia source), normal white blood cells, mainly polynuclear, (leuconeutropénie source of serious infections) and platelets (thrombocytopenia, a source of bleeding induced or spontaneous).
The leukemia cells can also invade other organs such as lymph nodes, spleen, liver, testicles or central nervous system.
Some hematologists put forward the idea that progress on leukemia are faster than for other cancers, with easy access to blood cells (a blood test), accelerating the research (see progress on leukemia).
* Decrease the number of white blood cells, causing serious infections repeatedly, as sepsis, severe angina
* Lower platelets resulting in bleeding gums, mucous membranes and subcutaneous tissue
* Fewer red blood cells, causing anemia, accompanied by pallor and palpitation
* Flooding by white blood cells of certain organs such as skin, resulting in the emergence of leucémides (large dark red blotches):
* Increased volume of lymph nodes
* Increased volume of the spleen (splenomegaly)
* Headaches and disorders of consciousness
* Facial paralysis
The four types of leukemia
The leukemia is clinically and pathologically split into two: acute and chronic leukaemia. And split depending on the origin of tumor cells: cells lymphoid and myeloid cells.
* The acute leukemia is characterized by the rapid proliferation of immature blood cells, abnormal histologically and ineffective. The acute leukaemia appear in children and young adults, immediate treatment must be made to avoid dissemination of these cells to all blood and organs.
* The chronic leukaemia, cancer cells here are more mature, although still abnormal and passing into the bloodstream, the evolution takes place over months to years. The tumor cells are created in greater numbers than normal but at the beginning sufficiently low so as not to cause death. The chronic leukaemia come mainly among the elderly. This type of leukemia can be treated later thus see for a period of time how changing and how the disease is made for a better deal.
Classification FAB acute leukemia
In early 1970, an international group consisting of researchers french, American and British officials worked on a new classification of acute leukemia in consulting hundreds of medical records of patients leukemia. This resulted in the classification Franco-American-British always used today to classify acute leukemia.
This classification recognized 3 different kinds of acute lymphoblastic leukaemia (ALL): L1, L2 and L3, and 7 subtypes of acute myeloblastic leukemia (LAM): M1, M2, M3, M4 and M4Eo, M5 and M6. Secondarily were added types M0 and M7. On the therapeutic LAL L1 and L2 are treated under the same protocols; type L3, also known as Burkitt's leukemia, is a different treatment.
For LAM, type M3 (acute promyelocytic leukaemia) has benefited from recent advances (use of acid all-trans retinoic or tretinoin and arsenic salts) and is treated according to specific protocols; other subtypes LAM will address the same way.
The classification FAB currently tends to be replaced by a new classification developed under the auspices of WHO (WHO classification).
The characterization of leukemia cells is supplemented by the study:
* Immunophénotype the research of the expression of certain markers on the surface of leukemia cells. For LAL it helps determine the nature of B or T proliferation;
* Karyotype research acquired chromosomal abnormalities of leukemia cells. Some of these abnormalities are specific to a particular subtype of leukemia, while others have a prognostic value;
* Their DNA and its transcripts (RNA): different types of examinations of molecular biology will complement the karyotype and seek some chromosomal abnormalities. In the near future will also be analysed all the RNA transcripts of leukemia cells has provided diagnostic and prognostic.
Treatment is variable depending on the type of leukaemia:
-- Acute leukemia are treated with intensive chemotherapy, which usually requires a hospital stay long enough. The aim is to destroy the abnormal cells (blasts), but the cells' normal ', especially some of them (bone marrow cells, scalp, digestive tract), are also sensitive. After intensive treatment, the patient, in particular, can no longer renew only the cells of his blood and his immune system: they say that the patient is then being aplasia, during this phase he needs many health care and in particular to support transfusion. The first cure is known cure induction, then come from consolidation and cures for certain leukemia, a maintenance treatment. A radiation (radiotherapy) of the brain is necessary in some cases. A bone marrow transplantation may be indicated in some types and forms with the most severe prognosis; graft is also generally indicated in case of relapse. The chances of successful treatment is variable depending on the age and type of leukaemia with chances of recovery are LAL for the child of 80%.
-- LAM3 is treatable through a combination of chemotherapy and differentiating agents: acid all-trans retinoic salts and arsenic. The chances of recovery are greater than 70%.
-- CML is currently treats (2006) initially by a drug, imatinib, which acts specifically on leukemia cells and which has revolutionized the care of this type of leukemia. Other treatment options are other medicines (hydroxyurea, interferon, aracytine…) and allogeneic bone marrow transplantation.
-- LLC, a development that has most often very slow, a treatment vary according to the evolutionary stage and patient age.
Progress on leukemia
According to a lecture by Professor Laurent Degos (haematology department, Saint-Louis Hospital in Paris) to the Foundation for medical research, advances in leukemia are faster than for other forms of cancer. One reason is related to the facility to test the effect of drugs: "it is much easier to multiply the effect of blood or bone marrow that make punctures or biopsies of tumors of the lung or liver disease. Today (2004) are available even called differentiating products that can standardize the behavior of a cell leukemia. The best example is the treatment of LAM3 by acid all-trans retinoic. The preventive role of differentiating these drugs is discussed. Although not strictly speaking a "vaccination" against leukemia, they represent a kind of functional equivalent".