Children in the UK and Republic of Ireland who are diagnosed with Wilms tumour – the most common children’s kidney cancer – are less likely to survive without relapse than those in Germany and France due to later diagnosis, finds a new study led by UCL researchers.
The study, published in JCO Global Oncology, compared tumour size and stage of cancer at diagnosis with survival chances of 3,176 children with Wilms tumour.
All the children were treated as part of an international clinical trial* that used a standardised treatment approach between 2002 and 2011. This included 636 in the UK and Republic of Ireland (ROI), 786 in Germany and 687 in France.
The study found that 57.7% of children were caught in the early stage** in the UK and ROI, with the remaining 42.3% diagnosed at the late stage**. Of these, a fifth of cases (18.2%) were at stage 4 – meaning the cancer has spread – when discovered.
Comparatively, nearly three quarters (71.1%) of children in Germany and 61.7% in France were diagnosed with early-stage tumours **.
Assessing the cancer, researchers found that the mean size of Wilms tumours in the UK at the time of diagnosis was 665 millilitres (mL), compared to 464mL in Germany and 525mL in France. This is indicative of later diagnosis.
Analysis showed, the five-year ‘relapse free survival’ for children with Wilms tumour confined to the kidney (stages 1-3**, or ‘localised’ disease) in the UK was 85.1%, compared to 90.4% in Germany and 90.8% in France. Furthermore, when the statistical analysis for children with localised tumours (stage 1-3**) took account of the variation in tumour size and stage, there was no significant difference between the UK and other countries in relapse-free survival chances and the overall survival rate was 93.0% (UK), 96.0% (Germany), 97.9% (France). This means that late diagnosis in the UK most greatly compromises the success of first line treatment.
For children whose tumours had already spread at diagnosis (stage 4 or metastatic disease), who received the strongest treatments, there were no survival differences found between the UK, France and Germany. Their five-year relapse-free and overall survival chances were 76.0%/82.1% (UK), 77.6%/85.5% (Germany) and 73.6%/84.7% (France), respectively.
Professor Kathy Pritchard-Jones (UCL Great Ormond Street Institute of Child Health), chief investigator for the study, said: “Despite the NHS target to diagnose 75% of all cancers at ‘early stage’ 1 or 2 by 2028, this research provides important evidence that we have a problem with later diagnosis of childhood cancers in the UK compared to other European countries. This affects the success rate of first-line therapies, which have been optimised to make them safer and more effective and reduce use of treatments likely to cause long term health problems. Promoting early diagnosis is one of the best ways to improve outcomes for children with cancer in our country.”
Wilms tumour is the most common type of kidney cancer in children and affects one in every 10,000 children globally, with around 85 children diagnosed in the UK each year. They are most common in children under 5 and typically affect one kidney.
Treatment for Wilms tumour is standardised across most of Europe. The countries that took part in this study registered almost every child who had been diagnosed in their populations between 2002 and 2011. As a result, survival comparisons between countries should be fair and unlikely to be affected by bias in patient recruitment.
Professor Pritchard-Jones added: “Early detection of childhood cancer increases each child’s chance of ‘cure at least cost’. With expected survival rates of over 90%, we aim to reserve use of radiotherapy and the ‘high risk’ chemotherapy drugs, that cause long term side effects, to those at greatest risk of relapse. For Wilms tumour, larger tumours are now considered higher risk and are treated with these stronger drugs. However, a safer way to address this is to diagnose the child’s cancer when it is smaller, so that the extra treatment is not indicated.
“In many European countries, including France and Germany, when parents are worried that their child has something wrong, they can take them to be assessed by a paediatrician who works in the community. Routine child health checks in these countries also include physical examination by a paediatrician at regular intervals throughout early childhood (up to age 5yrs), which is the typical age at which Wilms tumour occurs. Both acute and routine child health care in the UK are different, with parents having no direct access to first assessment by a doctor with guaranteed paediatric training.
“We have preliminary evidence that Wilms tumour is more likely to be discovered as an incidental finding in Germany versus the UK. Our next international study*** will now test this hypothesis with comparable prospective data collection from parents at the time of diagnosis about how their child’s tumour was first noticed and acted upon by a doctor, with participation across nearly the whole of Europe.”