To mark International Childhood Cancer Day (15 February), the International Agency for Research on Cancer (IARC) is highlighting some of the research that IARC scientists are conducting to understand and tackle cancer in children.
According to estimates from the IARC Global Cancer Observatory, in 2020 almost 280 000 children and adolescents (aged 0–19 years) were diagnosed with cancer worldwide and almost 110 000 children died from cancer. However, the actual numbers may be much higher, because in many countries childhood cancer is difficult to diagnose.
Leukaemia was the most common cancer type in children and the most common recorded cause of cancer death in children. In high-income countries, 80% of children with cancer are successfully treated and survive. This is not the case in many low-resource areas, where information is scarce, diagnosis is imprecise, and treatment is inaccessible. Because of inequalities between and within countries, many children with cancer die without access to proper diagnosis or treatment.
The high survival rates in high-income countries mean that the population of childhood cancer survivors is increasing. Many survivors of childhood cancer require lifelong medical follow-up, and some experience serious late effects, which include developing a new cancer. These and other specific features present unique challenges, which require further targeted research on childhood cancer survivors.
The need for cancer control at all ages, including in children, led the World Health Organization (WHO) to launch the Global Initiative for Childhood Cancer in September 2018, with support from St. Jude Children’s Research Hospital (USA), IARC, and other global partners. The initiative has the ambitious goal of achieving at least 60% survival for childhood cancer globally by 2030.
ChildGICR projectTargeting Childhood Cancer through the Global Initiative for Cancer Registry Development (ChildGICR)
One of the IARC-led programmes to support the WHO Global Initiative for Childhood Cancer is the Targeting Childhood Cancer through the Global Initiative for Cancer Registry Development (ChildGICR) project. The overall aim of this project is to improve the quality and availability of data on cancer in children, particularly in countries with limited resources.
Specific data are needed to monitor progress towards the goal of the Global Initiative for Childhood Cancer. These data are collected by population-based cancer registries. However, only about 15% of the world’s population of children are currently covered by such registries.
Researchers in the Cancer Surveillance Branch (CSU) at IARC have many years of experience promoting cancer registration and analysing the global burden of childhood cancer. St. Jude Children’s Research Hospital and CSU scientists are engaged in the ChildGICR programme to develop tools, build networks, and produce evidence to facilitate the establishment of new registries and to support the activities of existing structures.
To expand the capacity of childhood cancer registries, IARC and St. Jude organized an online ChildGICR Masterclass to train people from 19 countries in the principles of childhood cancer registration. The participants were empowered to develop teaching materials on seven topics, working in small groups and supported by experienced advisers. They also developed templates for future courses to be organized in their regions. Through the Masterclass, these future trainers built a solid network that will support them in disseminating their acquired expertise in childhood cancer registration within their regions and globally.
CRICCS projectCancer Risk in Childhood Cancer Survivors (CRICCS): understanding causes to target prevention
Together with international partners, CSU is also leading research into causes of second cancers in childhood cancer survivors. A second cancer is a new cancer, different from the first cancer. The Cancer Risk in Childhood Cancer Survivors (CRICCS) project was launched in November 2020 and is being conducted over a 3-year period. In collaboration with a large network of cancer registries, operating mostly in high-income countries, CSU and partners will calculate the risk of developing a second cancer and investigate the possible causes of second cancers, to facilitate their prevention. This project, supported by Children with Cancer UK, demonstrates the value of population-based registries for the prevention of second cancers. Cancer survivors and parents of children with cancer are represented in the Scientific Advisory Board of the CRICCS project.
Classification of paediatric tumoursIARC to publish the first WHO Classification of Tumours volume on childhood cancers
In a new video for International Childhood Cancer Day, Dr Ian A. Cree, Head of the Evidence Synthesis and Classification Branch at IARC, speaks about the first volume of the WHO Classification of Tumours series to specifically focus on the classification of paediatric tumours.
Cancer types that develop in children tend to differ in important respects from those in adults. Clinical specialists are needed to make the diagnosis (e.g. pathologists and radiologists) and to manage the condition (e.g. paediatric oncologists and haematologists). These specialists have long relied on the WHO Classification of Tumours series as authoritative reference books to inform the treatment of individual patients as well as research.
Previously, the series dealt with tumour classification from a more strictly organ-specific or system-specific perspective. The particular diagnostic and clinical challenges of paediatric tumours require a different approach. Therefore, this volume has been developed with a more integrated, cross-sectional perspective by experts in childhood cancer.
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FIRST WHO CLASSIFICATION OF TUMOURS VOLUME ON CHILDHOOD CANCERS
IARC investigates the role of nutrition in childhood cancer prognosis and late effects
The global burden of cancer in children is expected to rise, particularly in low- and middle-income countries where endemic rates of undernutrition are paralleled by a rapid increase in the prevalence of obesity. In children with leukaemia, poorer outcomes have been reported for those who experience either undernutrition or overnutrition. Thus, clinicians, particularly those in low- and middle-income countries, face a double burden of malnutrition while initiating treatment for cancer in children.
To better understand the relationships between cancer and diet, IARC scientists have started the first standardized multinational study of how nutrition and other lifestyle factors affect health outcomes in children and adolescents with acute lymphoblastic leukaemia (ALL), the most common cancer type in children. In a new video, Dr Inge Huybrechts, a scientist in the Nutrition and Metabolism Branch at IARC, explains the study in greater detail.
The study team aims to recruit almost 6000 children with cancer across different continents and income levels. The scientists will then collect biological samples and data about the children’s diets, body fat, and lifestyles throughout and beyond their treatment. This information will help researchers to find the answers to questions about the impact of nutrition and other lifestyle factors on cancer progression and prognosis, which have so far remained elusive. The findings will also provide insights into how toxicities during treatment may affect survivorship or lead to undesirable effects.
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Nutrition and childhood cancer
IARC investigates the causes of childhood cancer: environmental risks
The substances that people encounter in their daily lives can affect their risk of cancer. When researchers investigate the causes of childhood cancer, they must look beyond substances that the child may have been exposed to directly and also consider the child’s parents, including their activities and the chemicals that they may have come into contact with before conception or during pregnancy.
IARC scientists gather data on people’s activities and then analyse the associations between exposures and cancer occurrence. When the researchers use data from large enough groups of people in enough different parts of the world, they can draw well-supported conclusions about whether something is likely to affect the likelihood that people who were exposed to it will develop cancer compared with people who were not exposed to it.
The Environment and Lifestyle Epidemiology Branch (ENV) is one of the groups at IARC that examine environmental exposures and how they affect a person’s risk of developing cancer. In a recently published review article, ENV scientists found that maternal occupational pesticide exposure before conception or during pregnancy was associated with the risk of leukaemia in their children. Exposure to ionizing radiation was also found to be a risk factor, but strong evidence was found only for exposures at higher doses. Although there are other factors for which the evidence is suggestive, the causes of most cases of childhood leukaemia remain unexplained.
Molecular maps of cancer developmentIARC investigates the causes of childhood cancer: molecular maps of cancer development
When scientists study samples of blood and tissue collected after cancer has developed, it can be difficult to know whether the biomarkers and biological processes they see were the cause of the cancer or were caused by the cancer. The Epigenomics and Mechanisms Branch at IARC, in collaboration with partners in several countries worldwide, is using large collections of blood samples collected at birth to produce molecular maps of the DNA of newborn babies, before the development of disease. Each map enables scientists to create a molecular snapshot – a sort of diary – of early-life factors that the baby had been exposed to during pregnancy.
The period while a fetus is in the womb has a remarkable impact on human development, driven largely by epigenetic mechanisms – the molecular imprint of nature and nurture that shapes the different cells and organs. Unlike genetic mutations, epigenetic changes are potentially reversible, and thus they offer interesting targets to prevent disease before things go wrong.
Mapping the epigenomes in children with cancer from birth to diagnosis can reverse the arrow of time to explore the early origins of cancer. This could guide future preventive strategies and present a new generation of biomarkers, enabling health-care workers to identify children at high risk of developing cancer. This could also shed light on the molecular origins that drive cancer development, thus offering central targets for personalized therapy. A video explaining this research is now available in 11 languages: Arabic, Chinese, Croatian, English, French, German, Italian, Japanese, Portuguese, Russian, and Spanish. The videos are available here.
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Researching the origins of childhood cancer
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