Leukemia

The classification of leukemias is based on two main criteria:

The speed of progression:

• Acute: rapid progression with accumulation of immature cells (blasts) and rapid onset of symptoms. Requires rapid therapeutic management.
• Chronic: slower progression, with production of more mature but abnormal cells, sometimes asymptomatic for a long time.

The type of cell of origin:

• Lymphoid (or lymphocytic): originating from lymphocytes, cells that are essential to the immune system.
• Myeloid (or myelogenous): affects cells originating from the myeloid lineage, which produces red blood cells, certain types of white blood cells, and platelets.

These criteria give rise to four major forms:

1. Acute lymphocytic leukemia (ALL) – the most common in children, but also possible in adults.
2. Acute myelogenous leukemia (AML) – common in adults, often more aggressive.
3. Chronic lymphocytic leukemia (CLL) – predominant in older people, slow progression.
4. Chronic myelogenous leukemia (CML) – characterized by a specific chromosomal abnormality, the Philadelphia chromosome.

In addition to these forms, there are rarer types such as hairy cell leukemia, certain myelodysplastic syndromes, and myeloproliferative disorders.

Leukemia begins when a developing blood cell in the bone marrow undergoes a change in its DNA. This mutation alters the normal instructions that regulate cell growth and programmed cell death. Instead of developing and dying at a physiological rate, the abnormal cell continues to multiply uncontrollably.
In acute leukemia, the affected cell is often very immature and stuck at an early stage of development. It is unable to differentiate into a functional cell, leading to an accumulation of blasts that are unable to perform their role in the blood. In chronic leukemia, the abnormal cells are more differentiated, but their lifespan is abnormally prolonged, causing them to gradually accumulate in the blood, bone marrow, and sometimes organs.
Leukemic cells gradually invade the bone marrow and replace healthy cells. This process leads to a decrease in the normal production of blood cells: fewer red blood cells (anemia), fewer platelets (thrombocytopenia, leading to coagulation disorders), and fewer functional white blood cells (leading to immune deficiency), which increases the risk of infection.

In some cases, leukemia cells migrate to other organs (lymph nodes, liver, spleen, central nervous system, or testicles), a phenomenon sometimes compared to hematological metastasis. This spread is facilitated by the innate ability of blood cells to circulate and colonize new tissues, making the disease more difficult to treat.

The signs and symptoms of leukemia vary depending on the type, how fast it's growing, and how far along it is when it's diagnosed. In many cases, they're not very specific and can look like something harmless like a long flu, which can sometimes make it harder to catch.
The most common signs and symptoms include:

In certain forms, particularly acute lymphocytic leukemia, neurological symptoms may appear if the central nervous system is affected: headaches, visual disturbances, convulsions.

In children, the signs can develop rapidly, whereas chronic leukemias may remain asymptomatic for a long time and only be discovered during a routine blood test.

The exact cause of leukemia is often unknown, but the disease usually results from a combination of genetic and environmental factors. The process begins with DNA mutations in a developing blood cell. These abnormalities alter the signals that control cell growth and death, leading to uncontrolled multiplication and accumulation of abnormal cells.

These alterations can be spontaneous or occur after exposure to certain harmful agents. Known or suspected causes include exposure to high doses of ionizing radiation, contact with chemicals such as benzene, or the side effects of certain cancer treatments, particularly certain types of chemotherapy and radiation therapy.
Specific chromosomal abnormalities are associated with certain forms of leukemia, such as the translocation between chromosomes 9 and 22 (Philadelphia chromosome) in chronic myeloid leukemia.

Certain viral infections, such as Epstein-Barr virus or HTLV-1 virus, have been linked to specific forms of leukemia.
These mutations are not usually hereditary, although certain genetic predispositions exist in specific syndromes.

Certain factors increase the likelihood of developing leukemia, even though their presence does not systematically lead to the disease:

The diagnosis of leukemia is based on a series of tests designed to confirm the presence of abnormal cells and determine their type.
The first step often involves a blood test (complete blood count), which may reveal an excess or deficiency of white blood cells, a lack of red blood cells or platelets, and sometimes the presence of immature cells called blasts in the bloodstream.
To confirm the diagnosis, a bone marrow sample is taken by aspiration or biopsy, usually from the iliac bone. Morphological and immunophenotypic analysis is used to determine the cell line affected (myeloid or lymphoid) and the stage of differentiation of the leukemia cells.
Cytogenetic (karyotype, FISH) and molecular biology (PCR) tests are used to look for chromosomal abnormalities or specific mutations, which guide the prognosis and choice of treatment.
Depending on the case, imaging tests (X-ray, CT scan, ultrasound) can assess organ involvement, while a lumbar puncture can detect the presence of leukemia cells in the cerebrospinal fluid.

Treatment varies depending on the type of leukemia, the patient's age, general health, and the presence of specific genetic abnormalities.
For acute leukemias, chemotherapy is the first-line treatment. It combines several drugs administered in cycles to destroy leukemia cells and achieve remission. In some cases, targeted therapy or immunotherapy may be added, particularly for specific abnormalities such as the Philadelphia chromosome, which is treated with tyrosine kinase inhibitors (e.g., imatinib in CML).
Hematopoietic stem cell transplantation (autologous or allogeneic) may be offered when the disease is at high risk of relapse or resistant to conventional treatments. It involves replacing the diseased bone marrow with healthy cells after intensive treatment to eradicate the cancer cells.
Slow-progressing chronic leukemias can sometimes be monitored without immediate treatment until signs of progression appear. When the disease becomes active, treatments include targeted therapies, immunotherapy, or oral or injectable chemotherapy.
Supportive care (blood transfusions, antibiotics, pain management) also plays an important role in managing side effects and improving quality of life during treatment.

The progression of leukemia depends greatly on its type, how quickly it progresses, and how it responds to treatment.
Without treatment, acute leukemias can quickly lead to severe bone marrow failure and serious infections. Chronic leukemias, on the other hand, can remain stable for several years, but can progress to more aggressive forms or transform into acute leukemia.
Common complications include severe infections, which are exacerbated by neutropenia, and bleeding related to thrombocytopenia. Infiltration of certain organs (central nervous system, testicles, skin) complicates treatment and increases the risk of relapse.
Long-term side effects of treatment may also occur, such as heart problems, lung damage, or the development of other secondary cancers.
In some patients, the persistence of resistant leukemia cells, called leukemia stem cells, can cause late relapses. These cells are particularly difficult to eradicate and represent a major challenge for current therapeutic research.

There is currently no guaranteed way to prevent leukemia, as its exact causes often remain unknown. However, certain measures can reduce exposure to identified risk factors.

It is important to note that, in most cases, leukemia develops without any identifiable cause or possibility of strict prevention.

It is important to see a doctor promptly if you experience persistent unexplained symptoms such as unusual fatigue, repeated fevers, unintentional weight loss, frequent infections, or abnormal bleeding.
Signs such as swollen lymph nodes, discomfort under the ribs due to an enlarged spleen or liver, or unexplained bone pain should also be cause for concern.

In children, any combination of persistent fever, paleness, bleeding, and bone pain not related to trauma should be evaluated promptly. Early diagnosis significantly improves treatment outcomes.

At Hôpital de La Tour, leukemia is treated by a multidisciplinary team involving hematologists, oncologists, and supportive care specialists. Diagnoses are based on cutting-edge tests and personalized treatments reviewed during tumor board meetings. Comprehensive support is provided to patients throughout their care journey.

Is leukemia always fatal?
No. Some types of leukemia, particularly certain acute forms in children, can be cured. Others, such as chronic leukemia, can be controlled for many years with modern treatments.

What is the difference between acute leukemia and chronic leukemia?
Acute leukemia progresses rapidly with an accumulation of immature cells and requires immediate treatment. Chronic leukemia progresses more slowly and can remain silent for a long time.

Do symptoms always appear at the onset of the disease?
Not always. Some chronic forms can remain asymptomatic for years and be discovered during a routine blood test.

What is the Philadelphia chromosome?
It is a genetic abnormality specific to chronic myeloid leukemia and certain cases of acute lymphoblastic leukemia. It causes the production of a protein that promotes uncontrolled cell multiplication.

Is leukemia hereditary?
Most forms are not. However, certain rare genetic predispositions increase the risk of developing the disease.

Can leukemia be prevented?
There is no absolute prevention, but limiting exposure to toxic substances and unnecessary radiation and ensuring follow-up in cases of known risk can help reduce the likelihood of onset.

How is a bone marrow transplant performed?
It involves destroying the diseased marrow with chemotherapy or radiation therapy, then infusing healthy stem cells.

What should you do if you notice any warning signs?
You should consult a doctor immediately for a clinical examination and, if necessary, a blood test. The earlier the diagnosis, the better the chances of successful treatment.