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!