The leukemia is a cancer of tissues responsible for the formation of blood, that is to say of immature blood cells in the bone marrow (soft, spongy material in the center of most bones).
The disease usually starts with an abnormality in the formation of blood cells in the bone marrow. Abnormal cells (or leukemic cells) multiply and become more numerous than normal cells, preventing their proper functioning.
Types of leukemia
There are several types of leukemia. They can be classified according to the speed of evolution of the disease (acute or chronic) and according to the stem cells of the bone marrow from which they develop (myeloid or lymphoblastic). Leukemia usually refers to cancers of white blood cells (lymphocytes and granulocytes, the cells responsible for immunity), although some very rare cancers can affect red blood cells and platelets.
Abnormal blood cells are immature (blasts). They do not perform their normal function and multiply rapidly so that the disease evolves quickly too. The treatment must be aggressive and applied as soon as possible.
The cells involved are more mature. They multiply more slowly and remain functional for a certain time. Some forms of leukemia may go unnoticed for several years.
It affects granulocytes and blood stem cells present in the bone marrow. They make abnormal white blood cells (myeloblasts). There are two types of myeloid leukemia :
- Acute myeloid leukemia (AML)
This form of leukemia begins suddenly, often in a few days or weeks.
AML is the most common form of acute leukemia in adolescents and young adults.
AML can occur at any age, but is more likely to develop in adults 60 years of age and older.
- Chronic myeloid leukemia (CML)
The chronic myelogenous leukemia is also called myelocytic leukemia chronic or chronic leukemia grainy . This type of leukemia develops slowly, over months or even years. The symptoms of the disease are manifested as the amount of leukemic cells in the blood or bone marrow increases.
It is the most common form of chronic leukemia in adults between 25 and 60 years old. It sometimes requires no treatment for several years.
Lymphoblastic leukemia affects lymphocytes and produces lymphoblasts. There are two types of lymphoblastic leukemia:
- Acute Lymphoblastic Leukemia (ALL)
This form of leukemia begins suddenly and evolves rapidly in a few days or weeks.
Also called acute lymphocytic leukemia or acute lymphocytic leukemia , this is the most common form of leukemia in young children. There are several subtypes of this form of leukemia.
- Chronic lymphoblastic leukemia (CLL)
This form of leukemia most often affects adults, especially between 60 and 70 years. Affected individuals may have no or very few symptoms for years, and then have a phase in which the leukemic cells grow rapidly.
The causes of leukemia
The causes of leukemia are still poorly understood. Scientists agree that the disease is a combination of genetic and environmental factors.
In Canada, one in 53 men and one in 72 women will develop leukemia in their lifetime. In 2013, an estimated 5800 Canadians will be affected. (Canadian Cancer Society)
In France, leukemia affects around 20,000 people each year. Leukemia accounts for about 29% of childhood cancers, 80% of which are acute lymphoblastic leukemias (ALL).
Diagnosis of leukemia
Blood test. The analysis of a blood sample can detect whether the levels of white blood cells or platelets are abnormal, suggesting leukemia.
Biopsy of the bone marrow. A bone marrow sample removed from the hip can detect certain characteristics of leukemic cells that can then provide options for the treatment of the disease.
Symptoms of leukemia
The symptoms of the disease vary depending on the type of leukemia.
The symptoms of acute leukemia are usually not very specific and resemble those of other diseases such as influenza. They can appear suddenly in a few days or weeks.
The symptoms of chronic leukemia , in the early stages of the disease, are very diffuse or non-existent. The first symptoms appear gradually:
- Fever, chills or headaches.
- Weakness or persistent tiredness.
- Anemia, shortness of breath, pallor, palpitations (fast heartbeat), dizziness.
- Frequent infections (lungs, urinary tract, gums, anus, herpes or cold sores).
- A loss of appetite.
- Sore throat
- A loss of weight.
- Swollen ganglia, liver or swollen spleen.
- Bleeding (nose, gums, heavy menstruation) or frequent bruising.
- Small red dots on the skin (petechiae).
- Excessive perspiration, especially at night.
- Pain or sensitivity to the bones.
- Trouble of sight.
People at risk for Leukemia
- People with genetic disorders. Some genetic abnormalities may play a role in the development of leukemia. For example, Down syndrome, would be associated with a high risk of leukemia.
- People with blood problems. Some blood disorders, such as myelodysplastic syndromes ( bone marrow diseases), may increase the risk of leukemia.
- People who have a family history of leukemia.
- Having undergone cancer treatments. Certain types of chemotherapy and radiation therapy received for different types of cancer may increase the risk of developing certain forms of leukemia.
- Exposure to high levels of radiation. People exposed to high doses of radiation, such as survivors of a nuclear accident, are at high risk of developing leukemia.
- Exposure to chemicals. Exposure to certain chemicals, such as benzene (a product of the chemical industry in gasoline), would increase the risk of certain types of leukemia.
- The tobacco. Smoking cigarettes increases the risk of certain types of leukemia.
Factors such as exposure to low-level radioactive radiation, electromagnetic fields or pesticides in young children or during pregnancy may be risk factors for childhood leukemia. However, further research is needed to clarify their role in the onset of the disease.
Prevention of leukemia
|Can we prevent leukemia?|
|Studies show that there is a link between childhood leukemia and certain environmental factors (radioactive radiation, direct exposure to certain pesticides, prolonged exposure to electromagnetic fields, alcohol, and cigarette smoke). However, further research is needed to confirm these effects.|
Medical treatments for leukemia
The goal of leukemia treatments is to eliminate the malignant cells without affecting the normal cells of the bone marrow. Several researches are underway to develop the best possible treatments.
Depending on the type of leukemia, the age of the patient and his state of health, several treatment options are available. Treatments usually include several phases including:
Chemotherapy is a systemic treatment that circulates throughout the body and aims to destroy cancer cells and bring blood cell production back to normal. Different anticancer (cytotoxic) drugs are used depending on the type of leukemia.
Radiation treatments use high energy rays or particles to destroy cancer cells. This technique is used to treat or prevent the spread of the disease to the central nervous system and in preparation for a stem cell transplant.
Some drugs attack specific vulnerabilities of cancer cells. For example, in chronic myelogenous leukemia, a drug that inhibits tyrosine kinas (imatinibe, Gleevec in Canada, Glivec in France and Belgium) has become standard treatment, especially at the onset of the disease, and allows periods of remission of more than five years.
Transplantation or autologous transplantation of bone marrow or stem cells
After chemotherapy and radiation therapy, the patient is injected with bone marrow or stem cells to rebuild the bone marrow. Stem cells can come from a donor or from the patient himself (autograft ). This technique is used to treat people less than 55 years of age.
Different medications can be administered to control treatment-related complications, for example, antibiotics and antifungals to fight infections, blood products when the number of blood cells is low, growth factors to stimulate white blood cell production, drugs that reduce the high levels of certain chemicals in the blood, leukapheresis, to reduce the number of white blood cells.
Follow-up after treatment
Patients who have been treated for leukemia should be followed regularly for about 5 years, even if they have no signs of the disease.