Global burden of childhood cancer: growing, but controllable

There are many facets to the burden of childhood and adolescent cancer. Unsurprisingly, these are best documented in the predominantly high-income countries that have high-quality population-based cancer registries and death registration systems. In those countries, cancer is largely a disease of older adults, with well under 2% of cases diagnosed in the first 20 years of life (data from the Cancer Today database). More than half a century of progress in therapy and supportive care for children with cancer has resulted in impressive gains in survival and corresponding reductions in population mortality rates in high-income countries. However, this success has come at the price of increased long-term morbidity and mortality among survivors compared with the general population, which must also be counted as part of the cancer burden.1Fidler MM Reulen RC Winter DL et al.Long term cause specific mortality among 34 489 five year survivors of childhood cancer in Great Britain: population based cohort study.BMJ. 2016; 354i4351Crossref PubMed Scopus (82) Google Scholar, 2Bhakta N Liu Q Ness KK et al.The cumulative burden of surviving childhood cancer: an initial report from the St Jude Lifetime Cohort Study (SJLIFE).Lancet. 2017; 390: 2569-2582Summary Full Text Full Text PDF PubMed Scopus (388) Google Scholar In their Article in The Lancet Oncology, Lisa Force and colleagues3GBD 2017 Childhood Cancer CollaboratorsThe global burden of childhood and adolescent cancer in 2017: an analysis of the Global Burden of Disease Study 2017.Lancet Oncol. 2019; (published online July 29.)http://dx.doi.org/10.1016/S1470-2045(19)30339-0Google Scholar estimate, for the first time, the global burden of childhood cancer in disability-adjusted life-years (DALYs), taking into account loss of healthy life-years to ill health and disability in addition to death. The overwhelming majority of cases of cancer in children and adolescents (those aged younger than 20 years) occur in low-income and middle-income countries, which thus bear a correspondingly large part of the global cancer burden for this age group.4Bhakta N Force LM Allemani C et al.Childhood cancer burden: a review of global estimates.Lancet Oncol. 2019; 20: e42-e53Summary Full Text Full Text PDF PubMed Scopus (149) Google Scholar, 5Ward ZJ Yeh JM Bhakta N Frazier AL Atun R Estimating the total incidence of global childhood cancer: a simulation-based analysis.Lancet Oncol. 2019; 20: 483-493Summary Full Text Full Text PDF PubMed Scopus (137) Google Scholar A notable feature of the study by Force and colleagues is its stark demonstration of the absolute and relative scale of the burden in lower-resource countries and how it contrasts with that in high-income countries. High and high-middle Socio-demographic Index (SDI) countries account for 35% of global childhood and adolescent cancer incidence, but only 18% of DALYs, whereas low-middle and low SDI countries, with 38% of global incidence, account for 60% of DALYs. Worldwide, years of life lost represent 97·3% (95% uncertainty interval 97·3–97·3) of DALYs and years lived with disability only 2·7% (2·7–2·7), but the contribution of years lived with disability to total DALYs ranges from almost 9% (9–9) in high and high-middle SDI countries to less than 1% (1–1) in low-middle and low SDI countries. Force and colleagues note that their estimates probably understate the global burden of years lived with disability, and therefore of DALYs, because consideration of disability was limited to the first decade after cancer diagnosis rather than the entire remainder of the life course. How can the global burden of childhood and adolescent cancer be expected to evolve in the future, and what can be done to mitigate or even reduce it? As the population at risk increases—mainly in low-income to middle-income countries—the number of incident cases will also increase, and the total and proportional burden of childhood and adolescent cancer on lower-resource countries will become even larger. Childhood and adolescent cancer is much less amenable to prevention than many major cancers of adults, for which risk factors can be reduced or even eliminated. Immunisation against hepatitis B where it is endemic has resulted in a reduced incidence of liver cancer,6Chang MH You SL Chen CJ et al.Long-term effects of hepatitis B immunization of infants in preventing liver cancer.Gastroenterology. 2016; 151 (80.e1): 472Summary Full Text Full Text PDF PubMed Scopus (146) Google Scholar but most of the effect will be seen in adults, and liver cancer accounts for less than 2% of the global burden of childhood and adolescent cancer. Avoiding excessive exposure to ultraviolet radiation at young ages will lessen the risk of melanoma, but again principally among adults. In sub-Saharan Africa, the waning of the HIV epidemic should lead to a reduction in Kaposi sarcoma and progress against malaria could reduce the burden of Burkitt's lymphoma. The history of population screening for childhood cancer is not encouraging. The only feasible target was neuroblastoma, but screening led to overdiagnosis of cases that would have regressed without symptoms and had no effect on mortality from the more aggressive forms of this cancer.7Shinagawa T Kitamura T Katanoda K Matsuda T Ito Y Sobue T The incidence and mortality rates of neuroblastoma cases before and after the cessation of the mass screening program in Japan: a descriptive study.Int J Cancer. 2017; 140: 618-625Crossref PubMed Scopus (17) Google Scholar Earlier diagnosis through greater public and clinical awareness could bring a short-term rise in global burden for children and adolescents because fewer cancers with onset before the age of 20 years would actually be diagnosed after that age; this change would particularly affect cancers that can have a relatively protracted natural history, such as Hodgkin lymphoma and thyroid carcinoma. Overall, however, early diagnosis can bring substantial reductions in mortality and long-term morbidity. Although gains from early diagnosis should be greatest in lower-resource countries, where too many cases are diagnosed at a late stage, they should be felt even in affluent countries, notably for people with low-grade brain tumours, survivors of which bear a considerable burden of disability.8HeadSmart Be Brain Tumour AwareA new clinical guideline from the Royal College of Paediatrics and Child Health with a national awareness campaign accelerates brain tumor diagnosis in UK children—"HeadSmart: Be Brain Tumour Aware".Neuro Oncol. 2016; 18: 445-454Crossref PubMed Scopus (45) Google Scholar For the benefits of early diagnosis to be fully realised worldwide, it must be accompanied by improved diagnostic and treatment facilities with universal access. International collaboration will be an essential component of the necessary capacity building.9Arora RS Challinor JM Howard SC Israels T Improving care for children with cancer in low- and middle-income countries—a SIOP PODC initiative.Pediatr Blood Cancer. 2016; 63: 387-391Crossref PubMed Scopus (31) Google Scholar It is to be hoped that the present study will help to stimulate the necessary improvements, and future iterations can monitor their success. I declare no competing interests. The author alone is responsible for the views expressed in this Comment and they do not necessarily represent the decisions, policy, or views of Public Health England. The global burden of childhood and adolescent cancer in 2017: an analysis of the Global Burden of Disease Study 2017The GBD 2017 results call attention to the substantial burden of childhood cancer globally, which disproportionately affects populations in resource-limited settings. The use of DALY-based estimates is crucial in demonstrating that childhood cancer burden represents an important global cancer and child health concern. Full-Text PDF Open Access