Many cases in Asia and Africa are being missed and leading to children ‘dying at home’

Almost half of children with cancer are going undiagnosed and untreated, according to a new global study.

The research suggests that the situation depends on location: while only 3% of childhood cancer cases in western Europe and north America are thought to have been missed in 2015, the proportion rose to an estimated 49% in south Asia and 57% in western Africa.

“It means that a lot of these children unfortunately are dying at home untreated,” said Zachary Ward, first author of the research from Harvard University. “Cancer survival even among diagnosed cases is already poor in these countries, but it is going to be basically 0% for children if they are not identified.”

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Ward said many children faced difficulties accessing healthcare and, even if seen by doctors, their symptoms might be confused with other conditions such as TB or malaria.

“Once we started to consider really what the challenges are that these children face, it is not that surprising that we are missing so many of them in these countries,” he said.

Writing in the Lancet Oncology journal, Ward and colleagues in the US report how they built a computer model that took into account factors including statistics on cancer incidence as well as the probability of children in a given country accessing healthcare and getting an appropriate referral and diagnosis.

As a result, the team were able to estimate the number of diagnosed and undiagnosed childhood cancer cases in 200 countries and territories around the world.

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Data from cancer registries from 77 countries were then used as comparisons, allowing the team to adjust the model and make sure it worked well, with Ward adding that figures produced by the model chimed well with other estimates from high-income countries, further validating the approach.

The model suggests there were an estimated 397,000 cases of cancer worldwide in 2015 among those aged up to 14, with acute lymphoblastic leukaemia the most common type of childhood cancer. However, only an estimated 224,000 children were diagnosed with any form of cancer, meaning 43% of cases were missed.

The researchers say around 92% of all new childhood cancer cases occur in low- and middle-income countries, with a particularly high rate in the countries of western Africa.

Ward said that was largely down to a higher prevalence of particular types of cancer, including Burkitt’s lymphoma, adding that, while genetics could play a role, environmental factors such as exposure to malaria and the Epstein-Barr virus could also increase the risk of certain cancers.

When the team looked at future scenarios, they estimated there would be about 6.7m childhood cancer cases worldwide between 2015 and 2030 – but that 2.9m would be undiagnosed.

But Ward said there was hope. “The good news is that universal health coverage expansion, which a lot of countries have already committed themselves to, will help children access the health system,” he said, although he stressed the need for investment in cancer registries so progress can be tracked.

Importantly, he said, the study could help overturn misconceptions. “It is often said that childhood cancer is non-existent in developing countries where it is really because we have poor data in these countries,” he said.

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However, the study has limitations, including that the team only had cancer registry data for two countries in west Africa.

Dr Claudia Allemani, associate professor of cancer epidemiology at the London School of Hygiene and Tropical Medicine, said estimates like those in the new study could help to spur better strategies for cancer control. But, she said, cancer registries were vital.

“Only real world data can give us the true picture in a given country or region of the world,” she said. “Cancer registries must be given the legislative, political and financial stability to collect complete and high-quality data in a timely fashion.”