Childhood cancers resulted in 11.5 million years of healthy life lost globally in 2017, shows first study to quantify impact
Collectively, childhood cancers are the 6th leading cause of total cancer burden worldwide after adult cancers of the lung, liver, stomach, colon, and breast; and the 9th leading cause of childhood disease burden globally.
Around 11.5 million years of healthy life have been lost globally due to childhood cancer in 2017, according to the first analysis that quantifies the impact of childhood cancer in terms of years of healthy life lost to ill-health and premature death. Most or 97.3% of this global burden is related to premature death, with 2.7% due to impaired quality of life or years lived with disability, according to the first Global Burden of Disease Study (GBD) that evaluates childhood and adolescent cancer burden in 195 countries in 2017.
The study, published in The Lancet Oncology journal, estimates the number of years of healthy life that children and adolescents with cancer have lost due to illness, disability, and premature death - a measurement known as disability-adjusted life years (DALYs). One DALY is equivalent to one year of healthy life lost, explains the research team. The childhood age group in this analysis encompasses children and adolescents, defined as ages 0-19 years.
“While the number of new cancer cases in children and adolescents (0-19 years) is relatively low at 416,500 globally in 2017, treatment-related ill-health and disability and fatal cancer are estimated to cause around 11.5 million years of healthy lives lost globally every year. By presenting the global burden of childhood cancer through the lens of disability-adjusted life-years, we identified that childhood cancer results in a substantial disease burden despite a relatively low absolute number of incident cases and deaths,” says the research team led by Dr Lisa Force from St Jude Children’s Research Hospital (US), in collaboration with the Institute for Health Metrics and Evaluation.
Accurate childhood cancer burden data are crucial for resource planning and health policy prioritization, say the researchers. “Improving childhood cancer survival will require considerable planning by policymakers to ensure well-functioning health systems capable of early diagnosis and treatment. Estimating the years of healthy life children have lost due to cancer allows policymakers to compare the lifelong implications of childhood cancer with other diseases, potentially helping them determine the most effective way to spend limited resources and identify high-impact cancer-control planning decisions,” says the team.
In the study, global and regional estimates were analyzed using socio-demographic index (SDI), a measure based on rates of education, fertility, and income. Countries with high SDI have high levels of income and education and low fertility, whereas countries with low SDI have low levels of income and education and high fertility, says the team.
Childhood cancer is a leading cause of global disease burden
The researchers found that childhood cancers are a major cause of global disease burden compared with both adult cancers and other childhood diseases. Children younger than five years of age accounted for 37% of the total burden of childhood cancer (4.3 million DALYs). “The annual toll of childhood cancer (11.5 million years) compares with around 37 million years of healthy life lost globally due to malaria, and 7.6 million from tuberculosis. In 2017, childhood cancer was among the top four biggest contributors to the burden of general diseases of childhood in middle and high-middle SDI countries, ranking higher than malaria and HIV/AIDS,” says the study.
In 2017, childhood cancers were the sixth leading cause of years of healthy life lost out of all cancers globally (11.5 million), only lower than the burden from adult cancers of the lung (41 million), liver (21 million), stomach (19 million), colon (19 million), and breast (18 million). Further, childhood cancer was also the ninth leading cause of childhood disease burden globally. In low and middle SDI countries, childhood cancers were the leading cause of DALYs, higher than the burden attributable to any single adult cancer type.
Leukemia or blood cancer was identified as the primary disease driver, accounting for 34% of the total childhood cancer burden (0-19 year-olds) worldwide. This was followed by brain and nervous system cancers (18% in 0-14-year-olds), and rare cancers of the testes, ovaries, or thyroid (19% in 15–19-year-olds). “In 2017, the proportion of both leukemia and brain cancer burden differed by almost three times between regions. The proportional burden of leukemias was highest in central and Andean Latin America (49% of all childhood cancers), and the greatest absolute burden was in south Asia (954,000 DALYs),” says the team.
Children in the poorest countries are at most risk
In low- and middle-income countries (LMICs), children are four times more likely to die of cancer than children in high-income countries (HICs). The analysis shows that children in the poorest countries face a disproportionately high cancer burden - contributing over 82% of the global childhood cancer burden. This, say the researchers, is equivalent to almost 9.5 million years of healthy life lost in 2017.
“Children with cancer who live in HICs have good outcomes, with approximately 80% surviving five years after their diagnosis. However, over 90% of children at risk of developing childhood cancer each year live in LMICs. Considered by many as one of the major advances of modern science, the improvement in outcomes in children with cancer seen in HICs over the past several decades has not translated to most LMICs, where existing data suggest that far fewer children survive,” says the study.
The findings reveal striking inequities in childhood cancer burden between high and low SDI countries. High and high-middle SDI countries account for about 35% (147,300) of new cases of childhood cancer in 2017, but only 18% of DALYs (around 2 million years of healthy life lost). In sharp contrast, low-middle and low SDI countries with 38% of global incidence (159,600 new cases) account for 60% of DALYs (almost 7 million years of healthy life lost), according to analysis.
In a linked comment, Charles A Stiller from Public Health England (London), says: “The overwhelming majority of cases of cancer in children and adolescents (those aged younger than 20 years) occur in LMICs, which thus bear a correspondingly large part of the global cancer burden for this age group. A notable feature of the study 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.”
He adds, “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 tumors, survivors of which bear a considerable burden of disability.”
India, China, Nigeria, Pakistan, Indonesia face the largest burden of childhood cancer among countries with the highest population of children. According to the researchers, lack of diagnosis and access to healthcare and a younger population are responsible for the disproportionately large childhood cancer burden in many of the poorest countries. The USA had the sixth-largest burden in 2017, and sub-Saharan Africa had the biggest DALY burden for more childhood cancer types than any other region.
“The universal language of data offers a substantial opportunity to those fighting the global burden of childhood cancer. Analysis of the DALY burden by the individual country and cancer subtype shows the significant need for investment in data capture. Quality data collection and standardized reporting are crucial early strides towards better care provision for children with cancer in LMICs. Capture of national childhood cancer data can guide investments in the training of specialists to ensure earlier diagnoses, providing equitable access to medicines, reducing deaths, and improving survivorship care and quality of life,” state the editors of The Lancet Child & Adolescent Health journal in an editorial.