Exercise and maintaining a healthy weight during teenage years can significantly delay the development of breast cancer, a new survey claims.
Research published in journal Science shows that healthy living can delay the onset of cancer even among women with the highest genetic risk.
Women who carry inherited mutations in the genes BRCA1 or BRCA2 have a lifetime risk of breast cancer of more than 80 per cent, as well as a high risk of ovarian cancer, according to the most comprehensive study to date. Up to 10 per cent of women who develop breast cancer have inherited a genetic mutation in the genes, which play a role in helping to repair cell damage and prevent cancer.
The study of Ashkenazi Jewish breast cancer patients and their families by the New York Breast Cancer Study Group found that, even among the highest risk patients, 90 per cent of the inactive group were diagnosed by their mid-50s, while it took until the age of 70 for the same proportion of the active group.
"It was a surprise, but a source of hope, to learn that factors over which we have some control made a difference in the age at which these highest-risk women developed breast cancer," said Prof Mary-Claire King, of the University of Washington in Seattle.
Prof Larry Norton, of the Memorial Sloan-Kettering Cancer Centre, added: "The possibility that lifestyle changes such as increased exercise and weight control could modify the impact of genetic risk has very intriguing implications, not only for BRCA-related cancers but for other breast cancers as well."
The research team studied the genes of more than 2,000 people from families that each had one woman with breast cancer.