Blocking a key chemical can stop breast cancer spreading to other organs, experts have discovered.
Scientists at The Institute of Cancer Research (ICR) have found, for the first time, that a particular enzyme is involved in the spread of tumour cells from the breast to other parts of the body.
If experts can successfully block the action of lysyl oxidase-like 2 (LOXL2), then treatments could be developed to stop the spread of breast cancer.
Around 47,000 new cases of breast cancer are diagnosed in the UK each year and around 12,000 die from the disease.
Recent studies have shown that the lifetime risk of the disease for women is now one in eight.
Experts blamed lifestyle factors, including obesity and drinking alcohol, for fuelling the rise.
Women are also more likely to have children later in life and fewer offspring, which influences the risk.
In the latest study, published in the journal Cancer Research, experts found that LOXL2 promotes the spread of breast cancer through the way it controls two proteins, TIMP1 and MMP9.
Other studies have shown these proteins play a role in enabling cancer to spread.
LOXL2 has also been linked to the progression of other types of the disease, including colon and oesophageal cancer.
In the latest study, scientists found that blocking LOXL2 decreased the spread of breast cancer to the lungs, liver and bone.
According to lead researcher, Dr Janine Erler, from the ICR, more than 90% of cancer deaths are because the disease has spread to other organs.
"Our study shows that inhibiting the action of LOXL2 can significantly reduce the spread of breast cancer, suggesting that drugs which block this enzyme may be effective in preventing patients' cancer from spreading," she said.
Researchers also found that high levels of LOXL2 are linked with more aggressive cancer, which results in a poor prognosis for patients.
Holly Barker, postdoctoral fellow on the study, said: "This raises the possibility that we could develop a test to measure LOXL2 levels and predict patients who will develop aggressive disease.
"This knowledge could help us tailor treatment type and intensity to individual patients."
The study was carried out using laboratory tests, meaning further research is needed to confirm the findings.
Arlene Wilkie, director of research and policy at Breast Cancer Campaign, which funded the study with the ICR and Cancer Research UK, said: "Dr Erler's results are very exciting as, although currently we can treat breast cancer that has spread, we cannot cure it.
"By using LOXL2 to predict whose cancer will spread and drugs to block the enzyme to stop this from happening, many more lives could be saved.
"This laboratory research shows great promise and we look forward to seeing how it translates into patients."
Dr Julie Sharp, senior science information manager at Cancer Research UK, said: "The team have shown that targeting the molecule LOXL2, which plays a key role in spread, could offer new approaches to tackle this problem."