Scientists have developed a microchip to look for genetic signs showing how a form of a childhood nervous system cancer - neuroblastoma - may progress.
The technique could be tailored for different cancers
Some types of neuroblastoma are much more aggressive than others.
The Philadelphia team hopes identifying these will mean children at lower risk are not subjected to over-treatment.
Scientists told Genome Research their chip - which scans suspect sections of the genome for changes in the DNA - could be adapted for other cancers.
The chip developed by the team from the Children's Hospital of Philadelphia and Thomas Jefferson University scans neuroblastoma samples - a technique called microarray analysis.
Researcher Professor Paolo Fortina said: "We have customised this tool for neuroblastoma, but the approach might also be adapted to other types of cancer in which DNA changes are important."
Neuroblastoma, the most common cancer found in infants, strikes the peripheral nervous system, often appearing as a solid tumour in a child's chest or abdomen.
Specific genetic abnormalities have been shown to play a key role in determining whether the cancer is likely to be aggressive.
This can include the loss of one copy of a pair of genes - particularly when the gene involved helps to control cell growth.
The researchers had previously discovered that such an abnormality in a region of chromosome 11 often allows an aggressive form of neuroblastoma to take hold.
Thus they customised their new microchip to look out for this problem, among others.
The chip contains tightly ordered selections of genetic material upon which sample material can be tested.
When a particular genetic sequence is present it causes fluorescent tags to shine under laser light.
The new technique has so far only been tested in laboratory conditions.
Other forms of microarray analysis that have been developed measure the activity levels of genes by detecting levels of a genetic component called RNA.
The latest technique differs in that it identifies changes in DNA directly.
Dr Chris Redfern, of the Northern Institute for Cancer Research, told BBC News a team at his institute was also using gene chips to analyse changes in the DNA of childhood leukaemia samples.
But the idea of targeting specific areas of the chromosomes for analysis, rather than the whole genome, seemed new.
"This is significant as a factor to reduce costs - the whole genome chips are expensive, so producing customised arrays such as this is likely to be a lot cheaper," he said.
"As a tool for customising therapy to individual patients, it is likely to be quite powerful."
The UK Children's Cancer Study Group (UKCCSG) is also developing a gene chip that identifies the important genetic abnormalities in neuroblastoma.
Professor Andy Pearson, UKCCSG and a leading figure in the charity Cancer Research UK, said: "This kind of genetic testing will become an established part of treatment for children's cancer."