According to a recent Stanford study, simply being a close relative of a woman with a genetic mutation of the BRCA gene does not place a woman at a higher risk for getting breast cancer.
This new research, published last Monday in the Journal of Clinical Oncology, contradicts the findings of a 2007 study that claimed otherwise, suggesting women with a family history of the BRCA1 or BRCA2 mutation were more likely to develop breast cancer than the average woman, even if they tested negative for the mutation.
Breast cancer is the most common type of cancer among females in the United States, with roughly 230,000 new diagnoses of invasive breast cancer each year, according to the American Cancer Society. Men, on the other hand, have a one in 1,000 risk of developing breast cancer over the course of a lifetime. According to BreastCancer.org, while predicted deaths caused by breast cancer have declined since 1999 by 2 percent, this trend has only been seen in women over the age of 50. On average, 40,000 women die from breast cancer each year.
The average woman in the United States has a 12 percent chance of developing invasive breast cancer in her lifetime, meaning one in every eight women in the United States will be affected by breast cancer, according to BreastCancer.org. While about five to 10 percent of breast cancer cases are genetic, most of these are caused by abnormalities in the BRCA genes. Women with these mutations have up to an 80 percent increased chance of developing breast cancer, and as such, must take necessary precautions. Several options involve intensive annual screenings at an earlier age, taking the drug tamoxifen to prevent breast cancer or even undergoing a double mastectomy to diminish the risk before cancer can develop.
However, most women discover the mutation after they have been diagnosed with cancer.
Close female relatives may choose to test for the mutation if someone in their family has tested positive.
The 2007 study, published in the Journal of Medical Genetics, proposed that women who did not have the mutation but whose mother or sister did had up to a five-fold higher risk of developing breast cancer. As expected, these findings caused some anxiety among oncologists and patients.
As a result, the recent discovery brings great comfort to women from high-risk families.
“These findings put a lot of concerns to rest,” said Dr. Allison Kurian, assistant professor of medicine in oncology and health research and policy at Stanford Medical Center and author of the study.
Kurian studies breast cancer risks and prevention at the Stanford Medical Center.
Shortly after the publication of the unsettling 2007 paper, Kurian and her team put together an experiment to challenge the claims.
They studied more than 3,000 families with the BRCA1 or BRCA2 mutations from the United States, Canada and Australia and compared breast cancer rates between a control group of non-carriers of the BRCA mutation who had a first-degree relative with breast cancer and carriers of the mutated gene with first-degree relatives with breast cancer.
From this data, the study concluded that “if a woman tests negative for a BRCA mutation in her family, she does not have a significantly elevated risk of developing breast cancer.”
While both studies compared the risk of developing breast cancer in families with a history of the BCRA mutation, the study released in 2007 analyzed 277 British families with the BRCA mutation.
Kurian said she believed that the discrepancy between the two studies could be attributed to the fact that women in the first study were screened more often for breast cancer, and as such, more cases were found.