Scientists make major discovery in finding origins of aggressive breast cancer

The study, published today in the journal Cell Stem Cell, shows for the first time that the most aggressive and hard-to-treat types of the disease are likely to arise from intermediary, or progenitor, cells. The results run counter to the commonly-held theory that breast cancer originates in stem cells. This is hugely significant in directing future research into combating the disease.

Study leader Dr Matt Smalley, from the Breakthrough Breast Cancer Research Centre at The Institute of Cancer Research (ICR) in London, said: “These results represent a major advance in our understanding of breast cancer. It means we can now look very closely at where the disease forms and which genes are involved in that process. This knowledge will greatly improve the chance of finding effective new targeted treatments for breast cancer patients in the future.”

The team attempted to replicate inherited forms of human breast cancer in mice by giving them a faulty BRCA gene, which is known to cause the disease. They introduced the defect into the stem cells of one group of mice and into the intermediary cells of a separate group. The cancers which developed from stem cells did not resemble inherited breast cancer.

Strikingly, the cancers that formed from intermediary cells were almost identical to triple negative breast cancer and forms of the disease which run in the family. The authors therefore concluded that these types of breast cancer form in intermediary cells.

Triple negative breast cancer and breast cancer caused by faulty BRCA genes are two of the most aggressive types of the disease. They represent about 8,000 of the nearly 46,000 breast cancer cases in the UK each year. There is currently no targeted treatment for triple negative breast cancer, which is more common in younger women and black women. A targeted treatment for inherited forms of breast cancer, called PARP inhibitors, is currently showing promise in clinical trials.

Professor Alan Ashworth, Director of the Breakthrough Breast Cancer Research Centre at the ICR, said: “Understanding the biology of breast cancer is essential for the future development of new ways to treat and prevent the disease. Our research gives a considerable new insight into how the disease forms and grows.”