There is not one cancer, but more than 60 different types of pediatric cancers, which can be "grouped" into several families, including: leukemias, tumors of the central nervous system, lymphomas, carcinomas, germline and epithelial tumors, bone and extraosseous sarcomas, as well as various even rarer tumors. As in adults, cancer with one and the same name can hide specific realities and therapeutic needs.
The origins of pediatric cancers
Contrary to popular belief, cancer is rarely hereditary (less than 5% of cases). Only retinal tumors, as well as some very rare cancers could be found from one generation to the next due to a genetic predisposition. In other words, cancer can affect all children, without any geographic, social or genetic restrictions (over 95% of cancers are not hereditary).
While environmental factors favoring the development of cancer have been clearly identified in adults (alcohol, tobacco, toxic products, viruses, etc.), the origin of pediatric cancers is generally not known with certainty.
However, various realities suggest, in view of the increase in cases (incidence of + 1 to + 3% per year), that environmental causes could be involved in certain pediatric cancers: pesticides, electromagnetic fields, pollution, viruses, etc. -be an association of several of these factors. Fostering the development of epidemiological studies on childhood cancer would surely improve prevention and reduce the number of children to be treated.
Pediatric cancers have specific characteristics that are not found in adult tumors. While adults mainly develop carcinomas (cancers that develop from skin-like epithelial tissue), this type of cancer is very infrequent in children. In children under 15, we mainly find leukemia and lymphomas, cancers of the lymphatic system, brain tumors, so-called embryonic tumors.
These differences explain the often extreme rapidity of their growth, in a few weeks, sometimes in a few days, which is however not proportional to their severity. It is due to the high proportion of dividing cells in these tumors.
How to cure them?
A certain number of pediatric cancers “respond” to treatments (chemotherapy and radiotherapy) which are mostly developed for adults and “recycled” for children. For example, the survival rate of children with cancer is about 70% over 10 years.
This means that one in 4 children will not be cured. In addition, several studies show that these treatments are often very toxic and that the majority of children have sequelae, some of which are lifelong. Finally, many patients relapse due to the fact that the treatments do not kill all the cancer cells, which within the same tumor do not all have the same properties.
Some pediatric cancers are very different from adult cancers. This is the case with most brain tumors which are proportionately much more common in children. Finally, some cancers only exist in children and adolescents: this is the case with brainstem tumors.
Cancers specific to children may require "individualized", conventional, innovative (immunotherapy, gene therapy, etc.) treatments, or those resulting from the repositioning of the drug. Not to mention the role of surgery or bone marrow donation in leukemia. More generally, the role of fundamental and preclinical research is decisive, both for better understanding the mechanisms of childhood cancer and for proposing suitable therapeutic routes. Hence the absolute need to speed up research!
Brain tumors are a set of different diseases, which represent 20% of all childhood cancers: gliomas, medulloblastomas, rhabdoid tumors… These are the most frequent solid tumors in children. They are also those for which therapeutic progress has been the least important in recent decades. The survival rate of children with brainstem tumors has hardly changed over the last decades: it is less than 1% over 5 years.
Leukemias account for 30% of all malignancies. There are 2 main groups of leukemias in children: lymphoblastic leukemias which represent approximately 85% of cases and myeloblastic leukemia, which is rarer. Initiated in the 1970s, multidrug therapies make it possible to cure 80% of children with acute lymphoblastic leukemia. A bone marrow transplant, which makes it possible to replace the damaged bone marrow following the disease, or even by the treatments, can also be proposed. However, the disparities remain high and the consequences heavy. Acute myeloblastic leukemias have a cure rate of about 50%, while some infant leukemias have a very poor prognosis.
Osteosarcomas are the most common primary malignant tumor of the bone. Highly aggressive, they occur mainly in young people between the ages of 10 and 20. The majority of osteosarcomas occur in the knee, the lower end of the femur, or the upper tibia. Other locations are possible, most often on a long bone (humerus, fibula, etc.). The preferred site for metastases is the lung and then the other bones. Currently, the first chemotherapy, by methotrexate mainly allows a reduction of the tumor, followed by a surgical intervention allowing the resection of the diseased part of the bone. Metastatic osteosarcomas (which represent approximately 20% of cases) remain very difficult or even impossible to treat.
Ewing's sarcoma mainly develops in the bones of the pelvis, ribs, femora, fibula, and tibia. It has a strong invasive power and it is therefore not uncommon to see other cancerous foci appear in the body, especially in the lungs, skeleton and bone marrow. It often poses difficult therapeutic problems. Treatment is most often based on a combination of chemotherapy, radiotherapy and surgery. The overall cure rate is around 65%, but it is very uneven from one form to another. While the 5-year survival of localized forms of Ewing's sarcoma can reach 80%, it is less than 20% in metastatic forms.
Neuroblastoma is the most common extracerebral solid malignancy in young children. This tumor is characterized by extreme clinical and progressive variability, ranging from spontaneous regression without treatment to rapidly fatal progression. Neuroblastomas can be divided into 3 entities: neonatal tumors, whose prognosis is very favorable, localized tumors whose treatment is essentially surgical after possible tumor reduction chemotherapy; finally, metastatic tumors, in particular in the bone marrow and the skeleton, the survival rate of which has stagnated at 30%.
It is the most common soft tissue cancer in children, with a peak incidence between the ages of 2 and 5 years. Rhabdomyosarcomas affect boys more than girls and most often occur in the head and neck, more rarely in the genitourinary region or limbs, but can however affect all parts of the body. The therapeutic results are still insufficient, with very unequal chances of survival, on average 65%.
Nephroblastoma or Wilms tumor is a malignant tumor of the kidney, specific to early childhood, and very different from kidney cancer in adults. With nearly a hundred cases per year on average in France, it occurs most frequently between 1 and 5 years. More than half of nephroblastomas are treated with short chemotherapy followed by surgery (removal of the diseased kidney) and a few weeks of chemotherapy. Slightly more extensive forms should be treated without radiotherapy, but with more intense chemotherapy. About 25% of patients still need irradiation and aggressive chemotherapy. The survival rate is rather high, but the sequelae & side effects due to the treatments are numerous.
Lymphomas are cancers of the lymphatic system, which affect nearly 200 children each year in France. In children under 15, the most common type of lymphoma is "non-Hodgkin's". In adolescents and adults, it is more about Hodgkin lymphoma. During the last decade, efforts have mainly focused on reducing the volumes and doses of radiation and on the gradual elimination of the most aggressive drugs that generate sequelae. Overall 5-year survival is around 70%, which means that almost one in 3 children will not be cured.
A cancerous tumor of the eye, retinoblastoma affects the cells of the retina. Relatively simple, the diagnosis is sometimes still too late. However, clinical signs such as a white reflection in the pupil or the presence of strabismus are well known and must involve an ophthalmological examination as soon as possible. The precocity of the diagnosis conditions the implementation of treatments preserving the vision as well as possible. The Institut Curie is the reference center in France for the management of retinoblastoma.
It is about the disease which took away Eva, in January 2011, like 50 children / year in France. Brainstem tumors are tumors of the central nervous system belonging to the glioma family. This region of the brain that sits above the spinal cord is responsible for many vital functions, including vision, balance, strength, pharyngeal reflex, coughing, and swallowing. The tumor, depending on its size and location, can affect one or more of these functions.
Tumors located at the bridge affect the cranial nerves. They then cause symptoms related to the nerves that govern the muscles of the eye and face or involved in ingestion. Concretely this can result in strabismus, double vision, an inability to close the eyelids completely, difficulty chewing or swallowing ... The tumor also affects the "long passages" of the brain, which implies weakness in the arms or legs. legs, difficulty speaking, walking. In many cases, the symptoms worsen as the tumor grows quickly.
Tumors that arise in the peduncle usually affect the nerves controlling the muscles of the eye. They also block the flow of cerebrospinal fluid and increase intracranial pressure resulting in frequent headaches and vomiting.
Tumors affecting the bulb usually cause swallowing problems and weaken the arms and legs. The signs presented by the child can be diffuse and progressive: a dragging torticollis, headaches, pain in the lower head and neck, problems with walking, balance, paralysis of the face, of the eye when the cranial nerves are affected.
In France, children with brainstem tumors are either offered palliative treatment (radiotherapy), and possibly a biopsy (for scientific research) or participate in a clinical trial , as currently BIOMEDE. Unfortunately, over the past 40 years, none of them has improved the expectation of recovery.
Abroad, certain pathways are being investigated, sometimes allowing a marked improvement in survival expectancy: targeted surgical interventions, immunotherapy, etc.
Improving the resources dedicated to pediatric oncopediatrics research associated with strengthened collaboration between international teams could improve the survival of children with cancers that are now incurable in children.
die of cancer in France, i.e. 20 school classes. This figure has hardly declined for 20 years . Over the past decades, only pediatric cancers responding to “adult treatments” have seen their chances of recovery improve.
of children by disease. Leukemias, brain tumors and sarcomas clearly predominate.
For many pediatric cancers, including brainstem tumors, treatment often comes down to palliative care .
The number of childhood cancers increases by 1 to 3% each year, according to several European studies. One in 400 children will be affected by cancer before they come of age.
research on pediatric cancers, through INCa. This is why we want a law guaranteeing a public fund dedicated to research on childhood cancer in the amount of 15 - 20 million euros / year (in addition to existing resources) to be passed.
Industrial research is mainly focused on adult cancers, for reasons of profitability . However, malignant tumors detected in children are often different from those in adults and cannot be treated in the same way.
is very low for children with cancer. However, prevention makes it possible, in adults, to greatly reduce the number of cancers. Reducing the number of children diagnosed is essential.
are classified as “probable carcinogens” or even “ certain carcinogens ”, but remain freely available. They can be found in significant quantities in the environment or in the child's diet.
A woman who loses her husband is a widow; a man who loses his wife is a widower; a child who loses his parents is an orphan; no words exist for a parent who loses their child .