Blood testsA team of biologists believes it's on the path to developing a new early diagnosis test for difference cancers using tiny particles in the blood known as exosomes they've discovered contain huge chunks of DNA, according to

The team, from The University of Texas MD Anderson Cancer Centre, says we should be able to sequence the material from a blood sample to identify any number of genetic mutations that indicate cancer is present. They believe it will open up a new field of research, considering that the exosome samples tested were found to contain genomic DNA spanning across all chromosomes. 

Exosomes are tiny particles about the size of a virus shed by almost every cell in the body. The Texas team, led by Raghu Kalluri, decided to investigate the particles to see if they could potentially carry additional information about any cancerous cells in the body.

"We found they contain proteins, RNA, but while looking at these proteins and RNA we kept identifying some other things present in there - large fragments of DNA, which was really surprising to us. We didn't expect something that's present mainly in the nucleus of the cell to be present in these little particles," Kalluri said.

"We began looking at these fragments and found there were large quantities of them. So we began analysing them further and further and found these little particles contain the entire genomic DNA present in the nucleus, which is extremely exciting because now these little particles floating in the blood represent DNA coming from all kinds of tissues in the body -- it means you can probe the DNA to find out what's going on in those tissues, but you don't have to go to the tissue to get."

In the clinical study, written up in the Journal of Biological Chemistry, Kalluri and his team found that mutations commonly associated with pancreatic tumours - namely, mutations of KRAS, a protein that's key to normal tissue cell communications, and the p53 gene - were indeed identified in the DNA of these particles.