Key Takeaways
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October is Breast Cancer Awareness Month, and the statistic you’ll see most often is this one: about 1 in 8 women in the United States will develop breast cancer in her lifetime. Here’s a number you’ll see far less often. More than 80% of people who carry a BRCA1 or BRCA2 variant that raises breast, ovarian, prostate and pancreatic cancer risk have no idea they carry it.
Why So Many People Slip Through the Cracks
BRCA1 and BRCA2 are tumor suppressor genes, meaning their normal job is to repair breaks in your DNA before those breaks can lead to cancer. Everyone has both of these genes, but some people inherit a genetic variant that keeps one of these genes from doing that repair work properly. This raises the likelihood of breast, ovarian, prostate and pancreatic cancer. Those variants can be passed down from either parent.
Clinical guidelines generally recommend BRCA testing for people with a personal or family history of certain cancers. That sounds sensible until you look at who it misses.
Family history is easier to lose than many people assume. Small families, adoption, estranged relatives, donor conception or simply a branch of the family tree nobody talks about can lead to missing family history information. Ancestry information can get lost the same way. Three specific BRCA variants are much more common in people of Ashkenazi Jewish descent, roughly 1 in 40 people in that population have a BRCA variant compared to about 1 in 200 in the general population.
When 23andMe scientists studied more than 2,800 members who consented to research and had one of the BRCA variants in our BRCA1/BRCA2 (Selected Variants) Genetic Health Risk report*, 44% reported no close family history of a BRCA-related cancer. This means that nearly half of people with a BRCA variant would have been unlikely to qualify for clinical testing at all. In that same study, 21% of people with a BRCA variant reported no Jewish ancestry, yet 62% of them had detectable Ashkenazi Jewish genetic ancestry.
Men are also often missing from this conversation, and BRCA variants affect them too. Studies suggest around 7% of men with a BRCA2 variant and 1% with a BRCA1 variant develop male breast cancer in their lifetime, compared with about 0.1% of men overall, and BRCA variants also raise prostate and pancreatic cancer risk.
Finally, Black women in the US are about 38% more likely to die of breast cancer than white women despite being slightly less likely to be diagnosed with it. This disparity is shaped by access to care, time to treatment and tumor biology rather than by genetics alone. Most genetic research has been conducted in people of European ancestry, so detection rates vary by ancestry and polygenic models perform unevenly across populations. 23andMe has worked to narrow this, including a 2023 update that expanded our BRCA report from three variants to 44, improving detection for people of African American, East Asian, non-Ashkenazi European and Hispanic/Latino descent.
Inherited Risk Is Bigger Than One Famous Gene
BRCA1 and BRCA2 are the most famous genes connected to breast cancer, but inherited risk comes in more than one form.
While the 23andMe BRCA1/BRCA2 (Selected Variants) Genetic Health Risk report looks at 44 specific variants in the BRCA1 and BRCA2 genes more than 4,000 BRCA variants are known to increase cancer risk. However, BRCA1 and BRCA2 aren’t the only genes where inheriting a single variant matters. Researchers have identified other genes, including PALB2, CHEK2 and ATM, where one variant meaningfully raises breast cancer risk.
The 23andMe Breast Cancer PRS report** works from a third direction. A polygenic risk score, or PRS, is a statistical model that adds up the tiny effects of thousands of common genetic variants. No single variant contributes much alone, but together they can shift the picture, and it’s these common variants combined with lifestyle and environment that account for the majority of breast cancer cases. The Breast Cancer PRS report was built by 23andMe scientists using data from thousands of consented research participants and is available to 23andMe Premium Ancestry + Health members who self-reported their birth sex as female.
What You Can Do This Month
There’s a word for someone living with an increased likelihood of cancer who has not been diagnosed with it: previvor. Acting on that knowledge while you’re healthy is the entire point, and it starts with information that’s free to gather.
- Map your family history on both sides. Breast cancer risk can be inherited from your father as well as your mother, and paternal history is what people most often overlook. Note who had cancer, what kind and at what age. If your history is incomplete, that’s ok. Focus on the information you do have. Your own personal health records or genetic testing may provide additional helpful insights.
- Keep up with recommended screening. Mammography and other screening guidelines depend on your age and risk factors, so ask what applies to you.
- If your family history raises questions, ask about a broader clinical genetics panel. A selected-variant result that finds nothing does not rule out a variant it doesn’t test for.
- Tell your relatives what you find. Because genetic risk factors can be passed down through a family, sharing your own genetic information could help alert family members about a potential health risk they might have. Learn more about how to talk to family members about genetic results.
- Lean on the advocacy community. FORCE, Susan G. Komen, Breastcancer.org and Sharsheret all offer free education and support.
23andMe has returned BRCA risk information to more than 15,000 customers, and many may have never been offered traditional genetic testing. Start with the Genetics Learning Hub to understand how inherited cancer risk actually works, read customer stories of those who have found out about their cancer risk, then open your own reports and bring what you find to your next appointment.
* The 23andMe PGS test uses qualitative genotyping to detect select clinically relevant variants in the genomic DNA of adults from saliva for the purpose of reporting and interpreting genetic health risks including the 23andMe PGS Genetic Health Risk Report for BRCA1/BRCA2 (Selected Variants). It is not intended to diagnose any disease. Your ethnicity may affect the relevance of each report and how your genetic health risk results are interpreted. Each genetic health risk report describes if a person has variants associated with a higher risk of developing a disease, but does not describe a person’s overall risk of developing the disease. The test is not intended to tell you anything about your current state of health, or to be used to make medical decisions, including whether or not you should take a medication, how much of a medication you should take, or determine any treatment. Warnings & Limitations: The 23andMe PGS Genetic Health Risk Report for BRCA1/BRCA2 (Selected Variants) is indicated for reporting of 44 variants in the BRCA1 and BRCA2 genes. The report describes if a person’s genetic result is associated with an increased risk of developing breast cancer and ovarian cancer and may be associated with an increased risk for prostate cancer, pancreatic cancer, and potentially other cancers. The variants included in this report do not represent the majority of the BRCA1/BRCA2 variants in people of most ethnicities. This report does not include variants in other genes linked to hereditary cancers and the absence of variants included in this report does not rule out the presence of other genetic variants that may impact cancer risk. This report is for over-the-counter use by adults over the age of 18, and provides genetic information to inform discussions with a healthcare professional. The PGS test is not a substitute for visits to a healthcare professional for recommended screenings or appropriate follow-up. Results should be confirmed in a clinical setting before taking any medical action. For important information and limitations regarding each genetic health risk and carrier status report, visit 23andme.com/test-info/
** The 23andMe Breast Cancer PRS report is based on a genetic model that includes data and insights from 23andMe consented research participants and incorporates more than 2,000 genetic variants to provide information on the likelihood of developing breast cancer. The report does not describe a person’s overall likelihood, does not account for lifestyle or family history and has not been reviewed by the US Food and Drug Administration. The Breast Cancer PRS report is not intended to tell you anything about your current state of health, or to be used to make medical decisions or determine any treatment.
