Men who carry a faulty version of the BRCA2 gene have an estimated 1-in-15 chance of developing breast cancer by the time they reach 70, British scientists have found.
The faulty gene is already known to significantly increase the risk of breast cancer in women who carry it, but few studies have looked at its effect in men.
Scientists at St Mary's Hospital in Manchester and the University of Birmingham School of Medicine studied data on 321 families known to have BRCA2 mutations.
Among the 321 families, 20 men had developed breast cancer between the ages of 29 and 79.
There were 905 first-degree male relatives (parents or siblings) of known BRCA2 carriers, 2% of whom (16 men) had developed breast cancer.
Among second-degree relatives, there were eight cases of breast cancer, two of which occurred in men who were confirmed as having faulty versions of BRCA2.
Overall, the researchers calculated that men with the faulty BRCA2 gene had a 1-in-15 chance of developing breast cancer by the age of 70, and a 1-in-12 chance by the age of 80.
Based on research so far, the lifetime risk of breast cancer in men with a faulty BRCA2 gene is estimated to be between 6% and 9%.
In contrast, the lifetime risk of developing breast cancer for a man in the general population in the UK has been estimated to be about 1-in-1000.
Writing in the Journal of Medical Genetics, the researchers concluded: "These risks are sufficient to increase awareness of breast cancer among men in BRCA2 families and to stress the importance of early presentation with breast symptoms."
Nell Barrie, science information officer at Cancer Research UK, said: "Most men who have a relative with breast cancer will not be at an increased risk of developing it.
"This study looked only at men who carry a very specific faulty gene and the numbers of men who carry this gene are likely to be small. If a man has a very strong family history of breast cancer and is worried about his risk he should discuss it with his doctor."
Source: Cancer Research UK
