Researchers have found that mutations in a specific gene, PALB2, may result in a one in three chance of a woman getting breast cancer by age 70.

Researchers at the University of Cambridge looked at 362 members of 154 families with mutations in PALB2. Each family had at least one member with breast cancer. The study uncovered that of the 311 women with the genetic mutation, 229 of those had breast cancer. In men, 51 had the mutation and seven had the disease.

Previous research has already found that mutations in genes BRCA1 and BRCA2 also play a factor in breast cancer risk, and many physicians now screen for those mutations. Women with mutations in either of these two genes have a 40 to 70 percent chance of getting cancer. This is the same kind of mutation that actress Angelina Jolie admitted testing positive to last year, resulting in her choosing to undergo a full mastectomy.

This new research, however, sheds light on the PALB2 gene and how a mutation might affect breast cancer risk. Someone who has the mutation has a 35 percent chance of developing the disease by the time they reach their 70s.

This research also shows that a mutation in PALB2 results in a higher risk for younger women: their risk was nearly nine times greater for cancer than those without the mutation. The study also suggests that these mutations often result in a more aggressive recurring cancer that's often resistant to treatment.

"Now that we have identified this gene, we are in a position to provide genetic counseling and advice," says Marc Tischkowitz, who led the study. "If a woman is found to carry this mutation, we would recommend additional surveillance, such as MRI breast screening."

Researchers warned that these results are dependent on a family's history of cancer, and that many other factors play a part in risk for the disease.

"We're learning all the time about the different factors that may influence a woman's chances of developing breast cancer," says Peter Johnson, chief clinician at Cancer Research UK, one of the study's funders. ""This particular mutation doesn't make people certain to develop cancer, but it's another piece of information to help women make proper informed choices about how they may help to minimise their own risk."