Interview by Professor Devilee The interview was recorded in Madrid (Spain) at the Familial Cancer Congress organised by the National Spanish Cancer Research Centre (CNIO). Mutations in genes BRCA1 and BRCA2 are important risk factors for developing breast cancer. But other factors such as the number of children, obesity and breast density can also influence the development of the disease. Professor Peter Devilee, geneticist at Leiden University Medical Centre, explains the genetics and other lifestyle risk factors that can influence breast cancer. The European BRIDGES study is looking at how genetics and lifestyle factors interact and determine the individual risk of getting the disease.