About 5% to 10% of breast cancers are thought to be hereditary, caused by genetic mutations passed from parent to child. Three of the most well-known genes that can mutate and raise the risk of breast and/or ovarian cancer are BRCA1, BRCA2, and PALB2. Women who inherit a mutation, or abnormal change, in any of these genes — from their mothers or their fathers — have a much higher-than-average risk of developing breast cancer and/or ovarian cancer. Men with these mutations have an increased risk of breast cancer, especially if the BRCA2 gene is affected, and possibly of prostate cancer. Many inherited cases of breast cancer have been associated with mutations in these three genes.
You are substantially more likely to have a genetic mutation linked to breast cancer if:
- You have blood relatives (grandmothers, mother, sisters, aunts) on either your mother's or father's side of the family who had breast cancer diagnosed before age 50.
- There is both breast and ovarian cancer on the same side of the family or in a single individual.
- You have a relative(s) with triple-negative breast cancer.
- There are other cancers in your family in addition to breast, such as prostate, melanoma, pancreatic, stomach, uterine, thyroid, colon, and/or sarcoma.
- Women in your family have had cancer in both breasts.
- You are of Ashkenazi Jewish (Eastern European) heritage.
- You are African American and have been diagnosed with breast cancer at age 35 or younger.
- A man in your family has had breast cancer.
- There is a known abnormal breast cancer gene in your family.
Among other criteria, current guidelines recommend genetic testing for someone diagnosed with breast cancer if:
- there is a known mutation in the family
- the person was diagnosed at age 50 or younger
- the person has been diagnosed with two primary breast cancers
- a first-degree relative (mother, sister) was diagnosed with breast cancer at age 50 or younger or was diagnosed with ovarian cancer
- two or more first-degree relatives were diagnosed with breast, prostate, and/or pancreatic cancer
A study suggests that women who don’t meet breast cancer genetic testing guidelines are just as likely to have mutations linked to breast cancer as women who meet the guidelines. This means that a large number of genetic mutations linked to breast cancer are being missed.
The research was presented at the 2018 American Society of Breast Surgeons Annual Meeting on May 7, 2018. Read the abstract (scroll to page 22 of the linked PDF) of “HBOC patients who do not meet Medicare criteria for genetic testing have similar rates of clinically actionable findings as those who do meet criteria.” (PDF)
“These criteria do not adequately reflect evolving genetic knowledge, and they miss patients who should have increased cancer screening or should receive different systemic therapy,” said Jennifer Axilbund, of Invitae, a San Francisco-based genetic testing company, who presented the results. “Testing criteria should be broadened to included unaffected individuals with a positive family history and affected individuals with less severe presentation.”
To do the study, the researchers looked at the records of 1,990 people newly diagnosed with breast cancer who had Medicare as their insurance and who had genetic testing:
- 1,516 (76.2%) met the Medicare criteria for genetic testing
- 474 (23.8%) didn’t meet the criteria for genetic testing
People who knew they had a genetic mutation linked to breast cancer in their families were not included in this study.
All the genetic testing was done using multigene panel testing, which ranged from 9 to 80 genes tested. All the tests looked for mutations in the BRCA1 and BRCA2 genes.
The researchers compared the genetic test results of people who met the genetic testing criteria to the results of people who didn’t meet the criteria for genetic testing.
The researchers found that people who met the genetic testing criteria had slightly higher rates of BRCA1/BRCA2 mutations:
- 3.2% of people who met genetic testing criteria had a BRCA1/2 mutation
- 2.3% of people who didn’t meet genetic testing criteria had a BRCA1/2 mutation
Still, this difference was not statistically significant, which means that it could have been due to chance and not because of the difference in testing criteria status.
When the researchers looked at all the genes tested in the two groups, the rates of mutations also were similar for the two groups:
- 9.6% of people who met genetic testing criteria had a genetic mutation
- 7.8% of people who didn’t meet genetic testing criteria had a genetic mutation
This difference also was not statistically significant.
"Economically-based guidelines for genetic testing of breast cancer patients are anachronistic, miss a significant number of pathogenic variants, and we believe they should be abolished immediately," Peter Beitsch, M.D., of TME Breast Care Network in Dallas, said during a press briefing about the research.
If you’ve been diagnosed with breast cancer, you may want to talk to your doctor or a licensed certified genetic counselor about your diagnosis and your family history and ask if having a multigene panel test makes sense for you. A licensed certified genetic counselor or your doctor can help you understand the test and accurately interpret the results.
For more information on genetic testing, including types of genetic tests and how results are reported, visit the Breastcancer.org Genetic Testing pages.
For more information on genes and genetic mutations linked to breast cancer, as well as all the risk-lowering steps you can take if you have a genetic mutation, visit the Breast Cancer Risk Factors: Genetics page in the Breastcancer.org Lower Your Risk section.