NEW YORK (BBC Health News) -- U.S. researchers have developed a new technique to distinguish leukemia cells from healthy ones.

Though cancer cells do not look the same as normal cells, it can be tough for doctors to spot the difference.

A University of Florida team has developed a set of DNA probes which only stick to cancer cells, making it easier to identify them.

The Proceedings of National Academy of Sciences study could lead to improved early diagnosis of cancers.

Leukemia is the fifth most common cancer in the UK and accounts for about half of all cancers in children. Men are more prone to leukemia than women.

Cancer cells usually have genetic changes that modify the appearance of the cell.

Nine out of 10 tumor cases are diagnosed by pathologists, looking for these changes under a microscope.

Researchers have recently found that DNA can bind to proteins on the surface of cells.

Using this knowledge, the Florida team designed hundreds of DNA probes labeled with a fluorescent protein.

Following tests, they were able to identify those probes that stuck only to proteins found on the surface of cancer cells.

They were then able to identify the "labeled" cancer cells using a cell-sorting machine more accurately than could be done by the human eye using a microscope.

Personalized

The researchers are now trying to develop probes which will only stick to specific types of cancer cell.

This raises the possibility that the probes could be used to give a specific diagnosis of cancer sub-type.

The researchers do not actually know which specific proteins the probe actually binds to.

But they say this is an advantage, because it means that cancer cells can be identified without having to pin down the precise molecular markers which make them different from healthy cells.

Once the technology becomes more sophisticated, however, the researchers believe it could be used to identify slight individual differences among cancer patients -- allowing doctors to give more personalized treatment.

Researcher Dr. Ying Li said it might also be possible to use the technique to target drug treatments more precisely at cancer cells. He said: "If we have a marker that can recognize the tumor better than the normal tissue, the marker can be attached with a drug to do target therapy."

Ed Yong, cancer information officer at Cancer Research UK, said: "This is a promising start for what is essentially a completely new method for diagnosing cancer.

"If it proves to be successful in human trials, it could allow doctors to spot tumors much earlier and distinguish between subtly different cancer types. "As cancers are generally easier to treat when diagnosed early, this could save many lives."