Researchers from Strathclyde, Glasgow, and Napier universities have identified a sugar change in the blood which appears to signpost the disease.
Breast cancer kills more than 1000 people in Scotland each year and labs around the world are searching for a biochemical change – a biomarker – which could flag up the problem early.
A simple blood test could then be used to screen patients at risk from the condition.
US charity Friends for an Earlier Breast Cancer Test has given the Scottish scientists around £25,000 to investigate their discovery further.
Dr Kevin Smith, who will lead the next stage of the research at Napier University, said: “The Holy Grail of breast cancer research is identifying a molecule that not only appears to be diagnostic for an earlier detection of the cancer but which can also be detected by a simple blood test.”
The Scots scientists have identified a plasma protein which seems to have a role in other illnesses such as liver disease.
A type of sugar not usually contained in the protein was found in those patients with cancer and some of those with benign conditions. There was no sign of the sugar, N-acetylgalactosamine, in those who were disease free.
Gemma Gallacher, a PhD student at the Strathclyde Institute of Pharmacy and Biomedical Sciences who led the initial research, said although the findings were at a preliminary stage, they were potentially exciting.
She said: “If we could develop (a biomarker), it could detect the onset of breast cancer, dramatically improving survival rates.”