Every year, 150 children in the Netherlands are diagnosed with a tumor of the central nervous system – in the brain or spinal cord. Around half of these are malignant. Raoull Hoogendijk, clinical trial manager at the Trial and Data Center and PhD student in the Van Vuurden and Karim-Kos groups: ‘Research into better treatments for children with brain tumors is one of the strategic priorities for us at the Máxima. An important part of that research is to look at how the chance of survival improves over time.’
European study
A European study from 2017 showed that, compared to the European average, fewer Dutch children and young people with a malignant tumor of the central nervous system were still alive five years after their diagnosis. Raoull Hoogendijk: ‘People in the Netherlands immediately jumped to a reason: that’s because we register diagnoses better here. But is that truly the explanation? That’s what we wanted to explore further.’
Hoogendijk and colleagues – including group leaders dr. Henrike Karim-Kos and dr. Dannis van Vuurden – looked at data from the Netherlands Cancer Registry (NKR) of two thousand children diagnosed with a malignant tumor in the brain or spinal cord between 1990 and 2017. They also looked at data from 1,580 children with non-cancerous tumors – including pilocytic astrocytoma, a slow-growing tumor in the brain. Their research was published in the journal Neuro-Oncology Advances and was funded by KiKa and the Princess Máxima Center.
Improvement was not constant
Hoogendijk: ‘We saw that the average five-year survival for both tumor groups together improved over the past thirty years. But for malignant tumors, the improvement was not constant.’ The five-year survival rate decreased from 51 percent in the 1990s (1990-1999) to 47 percent at the beginning of this century (2000-2009). In the following period (2010-2017), survival rose again to 61 percent –that means around six in ten children were still alive five years after they were diagnosed.
‘It is possible that changes in the way we register the diagnosis influenced the survival rates,’ says Hoogendijk. ‘That’s why it’s important to check if there was a true dip in survival between 2000 and 2009. This information is not only important to properly find out about improved survival over time, but also in international studies comparing survival rates from different countries.’
Improved diagnosis and treatment
Five-year survival increased in the most recent period (2010-2017). The researchers want to know to what extent improved diagnostics and treatment contributed to the increased survival rates between 2010-2017. ‘There have been important developments in diagnostics: for example, imaging has improved and we’ve gained more insight into the molecular properties of the tumor and the associated course of the disease.’
That is why the researchers have started a follow-up study to investigate how the treatment of children with different malignancies in the brain and spinal cord in the Netherlands changed over time and how this is related to the improved five-year survival before the start of the Máxima. The first results of this project are expected this year. Hoogendijk: ‘It will take a few more years before we can also study the numbers after 2018 – the year the Princess Máxima Center opened its doors. Of course we hope and expect that the concentration and integration of care and research in the Máxima will soon be reflected as a further increase in the chances of survival.’