Acute childhood leukaemia

In this disease, there is an uncontrolled proliferation of immature white blood cells, known as blasts, which accumulate in the bone marrow and interfere with the normal production of blood cells. These malignant cells can enter the bloodstream and infiltrate other organs.

There are two main types of leukaemia:

Acute myeloid leukaemia, which affects the myeloid cell line from which red blood cells, platelets and other white blood cells (neutrophils, monocytes, eosinophils and basophils) derive.

• Acute lymphoblastic leukaemia, which affects the lymphoid cell line from which lymphocytes derive.
• Acute lymphoblastic leukaemia is the most common type and accounts for 80 % of paediatric acute leukaemias.

Symptoms

The most common symptoms at diagnosis are related to the accumulation of blasts in the bone marrow:

• Tiredness and pallor due to anaemia.
• Bruising or bleeding as a result of a low platelet count.
• Fever or increased susceptibility to infections due to neutropenia.
• Bone pain in long bones and/or joint pain caused by bone marrow infiltration.
• Enlargement of lymph nodes, the spleen and/or the liver.

Less common but characteristic symptoms may include testicular enlargement, neurological symptoms or skin lesions.

The disease usually presents as a subacute condition over days or weeks, with initially non-specific symptoms that may resemble those of other, more common illnesses. If these symptoms persist or worsen, leukaemia should be considered as a possible cause.

Diagnosis

The diagnostic process usually begins with a blood test, which may reveal abnormalities in white blood cell, haemoglobin and/or platelet levels. In some cases, leukaemic cells can be identified under the microscope.

The diagnosis is confirmed by bone marrow aspiration and analysis of the collected cells.

Most common diagnostic tests

• Full blood count and peripheral blood smear, to detect abnormalities in blood cell numbers and the presence of blasts.
• Bone marrow aspiration and/or biopsy, usually performed from the posterior iliac crest. The child is sedated to prevent pain. This test confirms the diagnosis and allows genetic studies to guide treatment and assess response.
• Lumbar puncture, which involves collecting a small amount of cerebrospinal fluid to detect leukaemic cells and administer intrathecal chemotherapy.

Additional tests may be carried out to assess involvement of other organs, including X-rays, ultrasound scans, echocardiography, eye examinations and blood tests.

Treatment

The aim of treatment is to eliminate leukaemic cells and prevent relapse.

The Paediatric Oncology and Haematology team at Vall d’Hebron selects the most appropriate treatment for each child based on the type of leukaemia, age, genetic characteristics of the leukaemic cells and response to treatment.

Chemotherapy is the mainstay of treatment and is usually administered intravenously, often via an implanted port (port-a-cath). Intrathecal chemotherapy is required because many drugs do not cross the blood–brain barrier.

In recent years, new treatments such as precision medicine and immunotherapy, including monoclonal antibodies and CAR-T cell therapy, have shown excellent results. Some are now being incorporated into first-line treatment protocols. Vall d’Hebron offers access to a range of molecular and cellular therapy clinical trials.

Prognosis

The prognosis of acute childhood leukaemia has improved significantly. Five-year survival rates in Spain are now around 87 %.

However, 15–20 % of children experience relapse, often requiring more intensive treatment and, in many cases, haematopoietic stem cell transplantation. New therapies continue to improve outcomes in this group.

Prevention

There is currently no known way to prevent childhood leukaemia. Although certain conditions increase susceptibility, the exact cause remains unknown. Environmental factors and viral infections have been investigated, but no clear evidence has been established.