A screening test costing as little as £25 has been developed that can test for cancer, a study says.
Cancer costs the NHS £4.3bn a year
The technology identifies gene abnormalities linked to the disease by profiling gene mutations in cells, the Nature Genetics journal said.
A US team from the Dana-Farber Cancer Institute tested 1,000 samples finding, as expected, mutations in a third.
The test is seen as a first step to personalised medicine in which therapy is tailored to different tumours.
But experts said there was still a long way to go.
Cancer currently costs the NHS £4.3bn a year to treat with around 280,000 diagnoses a year in the UK.
In the future, selected drugs could be targeted at a patient's specific set of genetic mutations.
Screening may also identify problems at an early stage, allowing action to be taken before a cancer develops.
Cancer is primarily a DNA disease, caused by defects within genes that govern cell growth and survival.
Several hundred to 1,000 of these mutations are now known.
Lead researcher Dr Levi Garraway said: "The challenge has been how to determine which of them are involved in each of the hundreds of kinds of cancer that occur in humans - and to develop accurate, affordable methods of detecting key mutations in tumour samples.
"This study suggests that such a method is feasible on a large scale."
The researchers used a technology known as high-throughput genotyping, which allows the rapid profiling of gene mutations within cells.
DNA is extracted from a piece of tumour tissue, copied thousands of times, and deposited into a number of "wells" on a small plate.
Special chemicals are then added to reveal which sample carries a specific mutation.
Automated equipment is used to "read" the plates and identify the mutations.
The scientists scanned 1,000 human tumour samples for 238 known mutations in 17 of the most common genes that may carry abnormalities linked to cancer.
They found at least one mutation in 298 of the samples, or 30% of the entire group, which fitted in with the rates seen in earlier studies.
Dr Garraway said: "Mutations were identified in the percentages we expected, which indicates this technique is on target for the mutations we were interested in."
And he said next step was to see how useful the technology is in a clinical setting, and the extent to which it may improve the ability of doctors to classify and treat individual tumours.
Henry Scowcroft, senior science information officer at Cancer Research UK, said: "Results like these show that we're making real progress towards being able to diagnose a person's tumour on a genetic level, and tailor their treatment accordingly.
"But we're not there yet. There's still an awfully long way to go in testing these techniques, so that they can be used to help cancer patients reliably, accurately and cost-effectively."