Owing to barriers to access and referral in health systems, nearly one in two children with cancer worldwide are never diagnosed and are likely to die untreated, reveals an analysis of childhood cancer cases in 200 countries.

The study, published in The Lancet Oncology journal, estimates that there are almost four lakh new cases of childhood cancer annually, while current records count only around two lakh. According to the team from Harvard University, 92 per cent of all new cases occur in low-income and middle-income countries, a higher proportion than previously thought.

"Health systems in low-income and middle-income countries are clearly failing to meet the needs of children with cancer," said Professor Rifat Atun. "Universal health coverage, a target of United Nations Sustainable Development Goals, must include cancer in children as a priority to prevent needless deaths," Atun added.

In 2015 there were 3,97,000 childhood cancer cases globally, compared to 2,24,000 that were recorded as diagnosed. This suggests that 43 per cent (172,000 cases) of global childhood cancer cases were undiagnosed. The most common childhood cancer in most regions of the world was found to be acute lymphoblastic leukaemia, accounting for around 75,000 new cases globally in 2015.

Further, the team estimates that between 2015 and 2030 there will be 6.7 million new cases of childhood cancer worldwide. Of these, 2.9 million cases will be missed if the performance of health systems does not improve. The researchers argue that current healthcare models, which concentrate treatment in a few specialised hospitals, are not enough.

By strengthening health systems more widely, well-functioning healthcare delivery networks could develop, reducing the number of undiagnosed children with cancer. "Accurate estimates of childhood cancer incidence are critical for policy makers to help them set healthcare priorities and to plan for effective diagnosis and treatment of all children with cancer," said Zachary Ward from the Harvard T.H. Chan School of Public Health.