A blood test that can detect breast cancer decades before the disease develops could be available in five years, scientists have announced.
The test could help doctors to identify women at high risk of the disease allowing them to take preventive medicines and switch to healthier lifestyles.
ITV News' Science Editor Lawrence McGinty reports the gene can be affected by environmental factors such as alcohol, smoking and pollution.
Researchers have identified a 'genetic switch', carried by one in five women, that doubles their risk of developing breast cancer.
Experts described the breakthrough by scientists at Imperial College London as "exciting" and said signs of the disease could be detected "many decades in advance".
Dr James Flanagan, who led the new research, said the test could be available in five to ten years. Dr Flanagan said:
The research was funded by the Breast Cancer Campaign.