Scientists from Institute for Cancer Research have discovered an enzyme that plays a critical role in turning breast tissue into tumours.
The enzyme called lysyl oxidase (LOX) has been found to stiffen collagen, a major component of the supportive tissue in the breast.
It causes the collagen to change in a process known as cross-linking, which makes the tissue more fibrous.
The team showed that blocking the enzyme significantly reduced size and frequency of tumors in mice.
Higher levels of LOX increased the levels of collagen in mammary glands, made the tissue stiffer and correlated with a higher number of tumors invading the breast tissue.
After using chemicals or an antibody to block the enzyme, they found collagen in the mammary glands contained fewer cross-links and was less fibrous.
The study suggests that breast tissue controlled by enzymes such as LOX was a key factor in cancer development.
"The enzyme triggers a clear physical change in breast tissue and, if we could stop this happening, we expect it would slow the growth of any cancers that did develop and make them easier to eradicate," BBC News quoted lead researcher Dr Janine Erler from the Institute of Cancer Research, as saying.
"This study may also help explain why the rate of breast cancer increases dramatically with age - aged tissues are stiffer and contain higher levels of abnormal collagen cross-links," said Professor Valerie Weaver of the University of California in San Francisco, who was also part of the team.
The study is published in the journal Cell.