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.