Leukemia is a type of malignant blood cell disease. Its main characteristic is the accumulation of abnormal young cells, called blasts, which occupy the space of normal blood cells in the bone marrow (the space within the bone known as the marrow or blood factory) or in other parts of the body, such as the lymph nodes, spleen, liver, central nervous system (brain and spinal cord), testicles, and eyes.
In children and adolescents, leukemias represent the most common type of cancer, with the acute forms being the most prevalent. The estimated incidence of leukemias is 3 to 4 cases per 100,000 children under 15 years of age, and their peak prevalence is in the age group between 2 and 5 years.
Leukemia subtypes in children
The main subtypes of acute leukemia are:
- Acute Lymphocytic Leukemia (ALL): affects lymphocytes and, among all leukemias, is the most common in childhood. If adequately treated after diagnosis, it has a survival rate of more than 80%, that is, it has a high probability of cure;
- Acute Myeloid Leukemia (AML): the rarest subtype in childhood. The cells involved in the formation of AML are those forming the white blood cells, excluding the lymphocytes, red blood cells, and platelets;
- Mixed lineage leukemias (undifferentiated): they can present at the same time cells of lymphoid and myeloid lineage.
- Chronic leukemias: rare in children. The main characteristic is cell overproduction with the characteristic of reaching the mature stage of cells. Chronic Myeloid Leukemia (CML) is diagnosed in approximately 3% to 4% of children;
- Juvenile Myelomonocytic Leukemia (JMML): a rare type of leukemia in childhood. It is part of the group of proliferative and dysplastic bone marrow diseases and is characterized by the presence of an increased number of monocytes.
Symptoms and Signs of Leukemia in Children
The main symptoms of leukemia in children are:
- Leg pain;
- Joint pain
- Feeling of extreme tiredness (fatigue);
- Purple spots (ecchymoses) and/or red dots (petechiae) on the skin;
- Enlarged lymph nodes or swellings;
- Abdominal pain (caused by enlargement of the liver or spleen)
- Increased volume of the testicles
- Subcutaneous nodules
- Change in kidney function (decreased urine volume, for example)
- Continuous lack of appetite; and
- Weight loss for no apparent reason.
Several leukemia symptoms can be common to other diseases. Therefore, it is important to be aware of all of them and seek medical help as soon as possible when they manifest.
Diagnosis of leukemia in children
The initial diagnosis of leukemia in children is made by analyzing the patient’s medical history and physical examination. During the medical consultation, lymph nodes, bleeding areas, bruising, and enlargement of the spleen or liver are investigated.
Next, tests are ordered. The first blood test ordered is the complete blood count, which shows if there are suggestive blood changes, such as the presence of blasts, low platelets, and/or anemia. Some details of it:
- Myelogram: identifies the presence of blastic cells in increased numbers in the bone marrow. It is also performed during treatment, to evaluate the body’s response;
- Flow cytometry and immunohistochemistry: performed with a sample of bone marrow or other body fluids, it makes it possible both to classify the leukemia and to monitor the response to treatment;
- Karyotype or cytogenetics (chromosome evaluation): in the bone marrow sample, chromosome analysis is performed with the objective of identifying genetic alterations that determine the risk of relapse of the disease, besides determining specific treatments according to the genetic mutations found; and
- Molecular biology: more sensitive than the karyotype, it evaluates the genetic mutations that occur in the chromosomes.
If the result of the myelogram is not conclusive, or the bone marrow aspiration does not provide a sufficient sample for examination, a bone biopsy, in which a bone fragment is removed with a bone marrow needle, may be necessary.
CSF examination may also be necessary. For the procedure, a small needle is inserted into the space between the bones of the spine at the level of the pelvis and a lumbar puncture is made to aspirate the cerebrospinal fluid (CSF), which circulates around the brain and spinal cord. The purpose of this test is to identify the presence of leukemic cells in the central nervous system.
The lumbar puncture is also performed to administer chemotherapeutic drugs into the spinal cord space in order to prevent or treat leukemia if it is present in the central nervous system.
Imaging tests are also requested for the diagnosis of leukemia in children. X-rays, ultrasounds, CT, and MRI scans, among other tests, are performed to evaluate the extent of the disease and whether it has spread to other organs and parts of the body.
The treatment for leukemia follows a specific protocol, according to the type of disease. It is carried out through chemotherapy, immunotherapy associated or not with radiotherapy, and bone marrow transplant. The duration of treatment varies from case to case.
Understand how each procedure can be useful in the treatment of leukemia in children:
- Chemotherapy: its action aims to destroy sick cells. Its possible adverse effects are nausea, vomiting, hair loss, mucositis (lesions in varying degrees in the mucous membrane of the gastrointestinal tract), and diarrhea. It is administered intravenously, orally, intramuscularly, or subcutaneously;
- Radiotherapy: it can be used as the main treatment for leukemia (for example: when it is located in the testicle), as a treatment to reduce the mass of the tumor before the definitive treatment, or as a preventive treatment to avoid relapse of the disease. Radiation therapy is indicated in the protocol performed before the bone marrow transplant, called conditioning. The most common side effects that can occur in the irradiated region are hair loss, nausea, vomiting, diarrhea, and fatigue;
- Immunotherapy: a more recent biological treatment, with versions still under study and with specific indications. It uses drugs that enhance the patient’s own immune system, making it recognize the tumor as an aggressive agent and destroy it; and
- Transplantation of hematopoietic stem cells. The stem cell is responsible for the formation of blood cells and is located inside the bone marrow; it is also called bone marrow. In specific situations, a stem cell transplant will be indicated and a search for a compatible donor will be necessary. When one is found, either in the family or in the bone marrow bank, the patient will receive chemotherapy, associated or not with radiotherapy, before receiving the bone marrow that will be infused as a transfusion into a large caliber vein.
It is important that all treatment options are always discussed with your doctor, as well as their effectiveness and possible side effects, to help make the decision that best suits each patient’s needs.
There is no way to prevent or perform blood tests or other screening tests for most children as a way to screen for leukemia before it begins to cause symptoms that lead to a doctor’s visit. The best way to early detection is to pay attention to possible signs of the disease and seek help immediately when you notice them.
There are some genetic conditions, such as Li-Fraumeni syndrome or Down syndrome, that predispose to the disease. Such predisposition can also occur in children who have been treated with chemotherapy and/or radiotherapy for other types of cancer and in children who have had organ transplants and are taking immune-suppressing drugs. The risk of leukemia in these children, although higher than in the general population, is still small.