And, she said, many of the effective chemotherapy drugs can't be used a second time because they may be too toxic to healthy cells if given repeatedly, and cancer cells can become resistant to some forms of chemotherapy.
"We use our best treatment at the time to try to ensure long-term survival, but if another breast cancer comes along, we may be limited," she said.
While women with BRCA mutations are known to have a higher risk of developing an additional cancer, Willey and her colleagues wanted to learn if women with a family history but no known BRCA mutations carried a similar risk.
The analysis included 119 women who were part of the Familial Cancer Registry. All of the women had been diagnosed with an initial breast cancer, and had decided to prophylactically remove the second breast.
When the researchers analyzed the breast tissue from the second breast, they found cancer about 10 percent of the time, regardless of whether or not a woman had a BRCA mutation.
If the normal breast cancer cells were atypical -- meaning they showed precancerous changes -- the risk of breast cancer jumped to about 50 percent over a lifetime for a woman with a family history of the disease, according to Willey.
"Not having a BRCA mutation doesn't let you off the hook," Smith noted.
"There's no question that family history is extremely important. Even without a BRCA mutation, we counsel women to consider prophylactic mastectomy if they have a strong family history," she added.
More information
To learn more about prophylactic mastectomy, visit the National Cancer Institute.
