Ground-breaking discovery into the genetic causes of breast cancer

Scientists have discovered 49 new common genetic changes which can lead to the development of breast cancer, more than doubling the number previously known. This ground-breaking research, conducted by Breakthrough Breast Cancer-funded scientists at The Institute of Cancer Research (ICR), will help medical professionals to identify women who have an increased genetic risk of developing breast cancer.

Rare changes to genes such as BRCA1 and BRCA2 lead to a high risk of developing breast cancer. This new research, published in Nature Genetics, shows there are many more common genetic changes that can occur in women and subsequently lead to an increased risk of the disease. Each of these genetic changes is only responsible for a small increase in breast cancer risk, but when combined they can have a substantial effect.

Genetic information from more than 45,000 women with breast cancer and a similar number of women without breast cancer was analysed from 51 participating studies; including significant data from Breakthrough’s Generations Study. By comparing the genetic changes in women who had developed breast cancer with those who had not, scientists were able to pinpoint the 49 new genetic changes.

Study author Professor Montse Garcia-Closas, a researcher from Breakthrough’s Generations Study at The Institute of Cancer Research (ICR), says:

“This research is a huge step towards understanding the causes of breast cancer. These findings will help us to predict who is at increased risk of developing the disease and who could benefit most from prevention strategies, such as lifestyle changes and chemo prevention, and early detection strategies, such as regular screening.

“In addition, these genetic discoveries will lead to a better understanding of breast cancer biology. This knowledge could help develop more targeted drugs to treat different forms of breast cancer - taking us one step closer to a future of personalised medicine.”

The findings come from two separate studies. The first looked at the development of all breast cancers and 41 new common genetic variants were discovered. The second focused specifically on ER-negative breast cancer, a group of breast cancers which is more aggressive (including triple negative tumours). In addition to the two common genetic variants already known about, scientists discovered four new common genetic changes which can lead to the development of ER-negative breast cancer.  This discovery is significant as very little is known about what causes this type of breast cancer.

Dr Julia Wilson, Director of Research at Breakthrough Breast Cancer, says:

“Before this research was carried out, we only knew of 27 common genetic changes which caused breast cancer; and now we know over 70.

"The research that Breakthrough Breast Cancer funds, such as the Generations Study, is so important because it provides our scientists with the information they need to make vital discoveries like these.”