Protecting the kidneys of children with cancer

Some children with cancer develop kidney damage. How can we detect this damage earlier and prevent it as much as possible? These are the questions at the heart of the PhD research that Paulien Raymakers-Janssen will defend today. Her work provides important new tools to better protect children's kidneys during and after cancer treatment. The first findings are already being applied in clinical care.

An increasing number of children with cancer survive their disease. As a result, reducing the long-term effects of treatment is becoming ever more important. The kidneys deserve special attention in this regard. More than one in three children with cancer develops acute kidney injury during treatment. Some drugs and intensive therapies can increase this risk.

Paulien Raymakers-Janssen works at the Wilhelmina Children's Hospital (WKZ) and carried out her PhD research in the Van den Heuvel-Eibrink group at the Princess Máxima Center. She studied kidney injury at different stages of treatment and in groups of children at increased risk, including children with kidney tumors and critically ill children in intensive care.

Identifying vulnerable kidneys at an earlier stage

One of the key conclusions of Raymakers-Janssen's research is that acute kidney injury can have long-term consequences. Even when blood tests show that the kidneys have recovered, damage may still remain undetected. As a result, kidney problems sometimes only become apparent years later.

‘That is precisely why it is important to carefully assess kidney function before and during treatment,’ says Raymakers-Janssen. ‘If we know which children are at higher risk and if we can detect kidney injury earlier, we can also take steps sooner to protect their kidneys.’

Early detection of kidney injury is crucial. Doctors currently often use the blood marker creatinine to assess kidney function. However, creatinine levels usually change only after damage has already occurred. NGAL, a protein that can be measured in urine, may indicate kidney injury at an earlier stage. This could enable doctors to intervene sooner and help prevent further damage.

From research findings directly into clinical care

The next step is to apply the study's findings in everyday clinical practice. This is already happening for children undergoing stem cell transplantation at the Princess Máxima Center. These patients face a relatively high risk of acute kidney injury, around 55%. The goal is to reduce this to 35%. Thanks to support from the Princess Máxima Center Foundation, doctors can now implement this new approach in practice.

During hospital admission, known risk factors and early signs of kidney injury, including urinary NGAL levels, are assessed three times a week. No additional blood samples or treatments are required. If a child's risk increases, the treatment team can, for example, adjust medications or pay closer attention to fluid balance and blood pressure.

The data collected will also be used to develop a ‘kidney injury index’, which will enable even more accurate risk assessment for individual children in the future. This tool combines multiple risk factors and clinical measurements to better predict which children are at risk of developing kidney injury. Ultimately, the approach is intended to also be implemented in other departments within the Princess Máxima Center and in other pediatric hospitals.

Paulien Raymakers-Janssen will defend her PhD thesis, Towards Preservation of Kidney Function in Children with Cancer, on Thursday, 3 September 2026. Her supervisors are Prof. Dr Marry van den Heuvel-Eibrink (Princess Máxima Center) and Prof. Dr Marta Fiocco (Princess Máxima Center and Leiden University). Her co-supervisors are Dr Roelie Wösten-van Asperen and Dr Marc Lilien (both Wilhelmina Children's Hospital).