Cancer Prevention Institute of California Study Blasts Myth all are at Equal Risk in Breast Cancer Families
Risk Lower than Previously Thought for some Women in Families with Breast Cancer History
 Not all women from families with a breast cancer history share the same high level of risk, according to a new study from the Cancer Prevention Institute of California (CPIC) and Stanford University Medical School. In the largest study of its kind to date, researchers have shown that close relatives of breast cancer patients with a mutation in the BRCA1 or BRCA2 genes — but who don’t have the mutation themselves — are not at higher risk of getting breast cancer than women with a relative with breast cancer that is not related to BRCA1 or BRCA2.
“This is positive and encouraging news for this group of women who have been told they were at greatly increased risk for breast cancer,” said CPIC Research Scientist Dr. Esther John, who led the California component of this study.
The analysis, led by Dr. Allison Kurian, assistant professor of Oncology and of Health Research and Policy at Stanford University School of Medicine and published this week in the Journal of Clinical Oncology, lays to rest a controversy that arose in 2007 with the publication of a study in the Journal of Medical Genetics. That study reported that women who tested negative for mutations in the BRCA1 or BRCA2 gene had a two- to five-fold increased risk of developing breast cancer if they had a close relative with that mutation, prompting many health care providers to encourage ongoing breast cancer surveillance for these relatives.
Mutations in the BRCA1 and BRCA2 genes are strongly associated with the development of breast or ovarian cancer, with carriers facing a five- to 20-fold increased risk of developing these cancers. Prior to the 2007 study, female relatives who were tested and found not to carry the family-specific mutation had historically been advised that their cancer risks are the same as those of other relatives in breast cancer families without BRCA mutations.
“Because of these results,” Dr. John said, “women who fit this profile no longer need to take extraordinary measures such as mastectomies based on a mistaken belief. I hope this study contributes to clearing up misunderstandings that have led many women and health care providers to greatly overestimate their risk.”
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