The main cause of childhood cancer is genetic mutations in cells that can lead to the appearance of tumors in different types of tissues and organs. These mutations can occur randomly during the embryo’s development.
Few childhood cancers are hereditary — about 10%. In these, a mutation present in one of the biological parents can lead to an increased risk of developing cancer in the children.
In both cases, identifying the main genes associated with different types of childhood cancer can help to diagnose early development of solid tumors and develop personalized treatments for each patient.
St. Jude’s Children’s Hospital, in the United States, created a program in 2010 to map the genome of the main types of childhood cancer in the world. The database, freely available in the cloud, contains information on more than 10,000 patients, with more than 12,000 complete genome sequences.
In Brazil, the Hospital do Câncer de Barretos, in the interior of São Paulo, is one of St. Jude’s partners in the program. According to the pediatric oncologist and director of the children’s unit, Luiz Fernando Lopes, one hundred children treated at the Brazilian institution will have their complete genome sequenced at the American hospital, for inclusion in this database.
The importance of having a database like this, he says, is to collect epidemiological, clinical and molecular data on all the tumors of children treated at the Barretos hospital and its 12 partners in Brazil. Genetic testing of children is offered free of charge at the hospital.
The center already has two genetic mapping panels for the main types of lymphoid and myeloid leukemia, which are very common in children. “All the children treated as of January 1st of this year will have their epidemiological data entered in the single bank and, in the future, also genetic data”, he explains.
The ACCamargo Cancer Center hospital, in São Paulo, already has a panel with 126 genes that may be associated with a higher risk of cancer in germ cells – such as breasts, ovaries, colorectal region, among others.
Among these genes, scientists at the entity’s CIPE (International Research Center) identified mutations potentially linked to Wilms’ tumor (or nephroblastoma, kidney tumor), whose incidence is one in 10,000 children, most in the age group of 2 to 5 years, explains researcher Dirce Maria Carraro, who coordinated the study.
According to her, the group also develops research on liquid biopsy to evaluate tumor DNA fragments dispersed in the circulation. This minimally invasive and very accurate technique can help in the diagnosis and identification of patients who need less aggressive treatments.
According to data from Inca (National Cancer Institute), in the triennium 2020-2022, 8,460 new cases of childhood cancer will be diagnosed each year. In general, childhood cancer cases correspond to 2% of the total population.
A study published in July 2021 in the journal Genetics in Medicine evaluated the effectiveness of screening for genetic markers for cancer in newborns in the US. The research found that, for a total of 3.7 million newborns, 1,803 developed a cancer predisposing syndrome by age 20, and early identification reduced the risk of death by 7.8%.
However, the scientific consensus is still not entirely in favor of performing random screenings in the pediatric population, as is done in adults for breast, prostate or ovarian cancers.
“Today, a great challenge is to be able to bring these molecular tools into everyday life, because there is a very large disparity of institutions at the national level. So the knowledge generated can help in the development of new drugs, but this is the future, not the present “, ponders Sima Ferman, head of Inca’s pediatric oncology service.
At Hospital Israelita Albert Einstein, genetic tests are also performed on pediatric patients treated at the oncology center to identify possible mutations.
“But there are some markers that are found very rarely, we have many types already known from the literature. [de mutações] that we look for in an endless number of patients and never find”, explains Vicente Odone Filho, pediatric onco-hematologist at the hospital.
Therefore, searching for all types of known mutations in childhood cancer patients is not always adequate, given the high cost of such tests and the limited chance of finding the markers.
“At Einstein we have wide access, but unfortunately the availability of these tests within the SUS is limited”, says Odone Filho.
According to Ferman, as research advances, the focus should be on the patient’s quality of life. Conventional therapies, such as radiotherapy and chemotherapy, he says, are still the most used, mainly because of the improvements that have taken place over the past 30 years in terms of dosage and control of toxicity.
“The cure rate currently in countries rich in childhood cancer is around 85%. In Brazil, we have some regions with rates very close to those of developed countries, but the national average is 65%.”
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