A new test that lights up a tumour’s DNA with brightly coloured fluorescent dye can predict a child’s chances of relapsing from cancer, a study in the Lancet reveals1.
Scientists funded by Cancer Research UK at The Institute of Cancer Research and The Royal Marsden Hospital studied children with a type of kidney cancer called Wilms tumour.
Children whose tumour analysis showed a telltale pattern of red and green light – indicating highly active cancer genes – had a hugely increased risk of relapsing from the disease after treatment.
Being able to pick out children who are destined to relapse is an important step forward, since it will allow doctors to closely monitor their progress and to treat them more effectively.
Team leader Dr Kathy Pritchard-Jones, of The Institute of Cancer Research, says: “This is preliminary work with a very new technique, but we believe it will have real clinical value in the future. Identifying children who are destined to relapse with current therapies will allow us to intensify their treatment early on and hopefully reduce the chance of their cancer growing back.”
Scientists believed that particular combinations of cancer genes affect a child’s chance of suffering a relapse of the tumour. Using the new technique, they lit up genes turned on in each tumour with luminous red dye and compared them with genes active in normal tissue – lit up green. A gene’s activity is controlled by the equivalent of a dimmer switch and those genes turned up highest were illuminated particularly brightly.
Tumour samples were analysed from 18 children at the Royal Marsden, of whom 10 had suffered a relapse. Researchers looked especially at a particular part of the genome – on chromosome 1 – that they thought might be important for a child’s chances of relapsing.
In all the cases where a child had relapsed, genes in this region were highly active and produced bright bands of fluorescence, while none of the children who remained healthy produced this pattern.
Researchers hope that this high-risk pattern may detect nearly all tumours that are destined to relapse. They are now working to identify the genes responsible for the high risk, with the aim of developing a test to predict at the outset of treatment those tumours requiring more or less invasive therapies.
Sir Paul Nurse, Chief Executive of Cancer Research UK, comments: “Until now, we’ve had at best a rough indication of whether a child was likely to have problems in the future. But this new technique will allow us to identify a small group of children who are far more likely than normal to suffer a relapse. It’s this improvement in prediction that makes it so useful and which will make such a difference to future patient care.”
Cally Palmer, Chief Executive of The Royal Marsdsen Hospital, comments: “Being able to make accurate predictions about a child’s future health after cancer will take much of the uncertainty out of treatment. Doctors will be able to give children at high risk of relapsing the best possible chance of surviving their disease, while giving the rest a confident all-clear.”
- The Lancet360 (9330): pp.383-386
Tissue samples for the study were obtained through the UK Children’s Cancer Study Group, which is funded by a consortium of cancer charities.
Genes that are switched on produce molecules of RNA, with the amount of RNA dependent on the gene’s level of activity. The new technique involved labelling molecules of RNA from Wilms tumours with red dye and those from healthy tissue with green. They were then added to normal chromosomes, in order to locate them in the genome. Genes switched on to high levels were bound by large numbers of fluorescent RNA molecules and so were illuminated brightly.
Children who relapse from Wilms tumour often have cancers with an extra piece of one of their chromosomes – called 1q. Scientists therefore concentrated on the genes that lie on this piece.