A routine test could soon help doctors predict when and where treated breast cancer is likely to return.
Scientists have found molecular clues in breast tumours that indicate how the disease is likely to progress.
The information includes the likelihood of the disease recurring after treatment, and after what amount of time.
The Cancer Research UK team looked at genetic changes in tumours from almost 2000 women with breast cancer and followed their progress over 20 years.
Although the genetic analysis is too detailed to be of help to patients, the scientists are working on a more practical routine test.
Once developed it should pave the way to tailored treatments that improve women's chances of survival, they claim.
The test could be ready in about five years, according to the team.
Lead researcher Professor Carlos Caldas, from the Cancer Research UK Cambridge Institute, said: "Treatments for breast cancer have improved dramatically in recent years, but unfortunately for some women, their breast cancer returns and spreads, becoming incurable. For some, this can be many years later - but it's been impossible to accurately predict who is at risk of recurrence and who is all clear.
"In this study, we've delved deeper into breast cancer molecular sub-types so we can more accurately identify who might be at risk of relapsing and uncover new ways of treating them."
The research is reported in the journal Nature.
The scientists found that progression patterns varied greatly even between tumours that seem similar.
They identified subgroups of women with the most common form of hormone sensitive breast cancer who were at higher risk of the disease returning after as long as 20 years.
Each year around 55,000 new cases of breast cancer are diagnosed in the UK, making it the most common type of cancer in the country.
Two thirds of women with breast cancer in England and Wales survive for 20 years or more but the disease still causes around 11,400 deaths each year.
