Thousands of blood samples kept by a doctor could be the key to developing a single blood test to detect cancer.
Scientists are trying to identify a "cancer fingerprint" in the samples
Scientists at University of Southampton are now examining the samples, which were taken from 11,000 women in Guernsey over the past 30 years.
Some of the women later developed cancer and the research has been able to spot the disease in the blood by identifying certain tell-tale signs.
It is hoped the study could lead to "the holy grail" of cancer diagnosis.
Dr Paul Townsend, of University of Southampton, said: "Already we have seen significant bio-markers of breast cancer in the samples.
"The quality of the samples we have from Guernsey has been the key but it is early days."
He said a single cancer test "would be fantastic, it would be faster, more certain and less invasive".
The scientists can measure certain proteins in the blood samples and identify a characteristic "cancer fingerprint" in the women who went on to develop cancer.
Most cancers are only diagnosed with scans after the patient begins to feel ill or feels a lump or spot.
It is hoped that it will soon be possible to have a single blood test which will be able to identify these characteristics and diagnose the early signs of cancer.
But researchers admit it could be years before a test is widely available to doctors to use as a diagnosis tool.
The doctor in Guernsey began collecting the samples in the 1960s, hoping that such a resource might prove useful to future research.