Breast cancer link to Father's genes.

Byline: By Jon von Radowitz

Women can be at serious risk of breast cancer if they inherit faulty genes from their father, scientists revealed today.

A major study which revised risk estimates for inherited breast cancer showed fathers as well as mothers can pass defective BRCA1 and BRCA2 genes on to their daughters.

Researchers who investigated more than 1,000 breast cancer patients and their families found that women with BRCA mutations had an 82pc lifetime risk of developing the disease.

Previous estimates had varied between 25pc and 80pc for women from families with many cases of breast cancer.

But in the new study, half the 104 women found to have the gene mutations did not have a history of breast cancer in their immediate family. In nearly all these 52 cases the cancer-triggering defect had come from the father.

Chief researcher Professor Mary-Claire King, from the University of Washington in Seattle, said: "Mutations in BRCA1 and BRCA2 are inherited from fathers as often as from mothers, although fathers are rarely affected with breast cancer. So if a family is small, there may be no warning that a mutation is present."

All the patients tested by the New York Breast Cancer Study Group were Ashkenazi jews - a lineage originating in Germany and eastern Europe. They were chosen because their genetic make-up facilitates looking for BRCA mutations. But the researchers say the results should apply to all women who inherit the same faulty DNA.

The findings, reported today in the journal Science, showed that 10pc of all the breast cancers studied and 35pc of those diagnosed under the age of 40 were attributable to BRCA 1 and 2. Within the US population generally, about 7pc of breast cancers are linked to the genes.

"Lifetime risk" meant the risk of developing breast cancer by the age of 80.

Women with BRCA mutations had a 20pc chance of developing breast cancer by the age of 40, and 55pc by the age of 60.

But the study also found that older women born before 1940 were less likely to develop breast cancer, even with a strong genetic risk.

This suggests that environmental factors play an important role even with inherited disease.

Physical exercise and healthy weight during adolescence also appeared to offer protection against the disease.

In Britain, about 39,000 women are diagnosed with breast cancer each year and 12,000 die from the disease. However only between 5pc and 10pc are women with BRCA mutations.