People who inherit mutations in the BRCA1 or BRCA2 gene are at heightened risk for a variety of cancers, including breast, ovarian, prostate, and pancreatic. It’s estimated that one in 300-400 people in the general population carry a mutation in either of these genes. Among people of Ashkenazi (Eastern European) Jewish descent, the prevalence is about 2% (or one in 40) — still low, but ten times higher than in the population at large.
How much does a BRCA mutation increase cancer risk?
Not everyone with a BRCA gene mutation will develop cancer but inheriting such a mutation substantially increases the risk that cancer will occur, particularly at a younger age. Some examples:
- Women with a BRCA mutation have a 45%-72% chance of developing breast cancer in their lifetime and an 11%-44% chance of developing ovarian cancer, with higher risks in BRCA1 carriers according to the National Cancer Institute. That compares with a 13% lifetime risk of breast cancer and a 1.2% lifetime risk of ovarian cancer for women in the general population.
- The lifetime risk of prostate cancer in men with BRCA mutations is about 20%-60% (much higher in BRCA2 carriers), compared to 12% for men at average risk.
- Men with BRCA mutations have a 2%-7% risk of developing breast cancer over their lifetime, compared to 0.1% of men in the general population.
- The lifetime risk of pancreatic cancer is about 5%-10% for men and women with a BRCA mutation, compared with about 1% for people at average risk.
When should Ashkenazi Jewish people consider genetic testing for BRCA mutations?
Genetic counseling and testing are advisable for those who:
- Have a first-degree relative (parent, sibling, or child) who has been diagnosed with a cancer associated with BRCA mutations, especially if they were younger than age 50 when diagnosed;
- Have two second-degree relatives (grandparent, aunt, uncle, niece, nephew, or cousin) on the same side of the family who has been diagnosed with one of these cancers. Experts at Dana-Farber’s Center for Cancer Genetics and Prevention can help individuals understand their risk and steps they can take to lower that risk.
- Are considering having children, even if their family history of BRCA-related cancers is limited. Tests for BRCA mutations can be conducted along with tests for other genes that are frequently mutated in individuals of Ashkenazi Jewish descent, such as genes associated with Tay Sachs or Canavan diseases.
Family cancer history may not be very accurate, especially for abdominal malignancies like ovarian and pancreatic cancers. Families may think of them as “stomach” cancers.
How do I know if I have Ashkenazi Jewish heritage?
About 95% of American Jews are of Ashkenazi or Eastern European background. For these purposes, even one grandparent of Jewish ancestry would be sufficient to consider genetic evaluation.
Are Ashkenazi Jews the only group with an increased risk of inheriting BRCA mutations?
Studies suggest that people of Dutch, French Canadian, Icelandic, and Norwegian extraction may also be more likely to carry certain BRCA mutations.
About the Medical Reviewer
Dr. Garber is the Susan F. Smith Chair and Chief of the Division of Cancer Genetics and Prevention at Dana-Farber Cancer Institute and a Professor of Medicine at Harvard Medical School. She conducts research in clinical cancer genetics, with a special focus in genetics of breast cancer. Dr. Garber is also a leader in research into the characteristics and treatment of triple negative breast cancer, the most common form in women with BRCA1 mutations and an expert in Li-Fraumeni Syndrome. Her translational research focuses on the evaluation of novel agents targeting DNA repair defects in breast cancer, including PARP inhibitors for treatment and prevention of breast cancer and other BRCA-associated cancers, and the study of other agents for reduction of breast cancer risk.
Dr. Garber is a past president of the American Association for Cancer Research (AACR). She served on the National Cancer Advisory Board of the National Cancer Institute and was elected into the American Society of Clinical Investigation, the American Association of Physicians and the National Academy of Medicine. She serves as the Scientific Director of the Breast Cancer Research Foundation and is a past chair of the Breast Cancer Research Foundation Scientific Advisory Board. She is an ASCO Statesman and a Fellow of the AACR Academy, and was its first president.