Breast Cancer | Genetic Testing
How does genetic testing for breast cancer risk affect treatment and prevention?
More research supports the benefits of genetic testing for breast cancer risk
Genetic tests for inherited cancer risk look at gene changes that may directly inform healthcare decisions. They can help you consider risk-reducing measures like more frequent screenings. And for people who already have a cancer diagnosis, it can help inform treatment, including surgical strategy and the potential use of targeted therapies.
You might remember how, in 2013, Angelina Jolie brought widespread attention to how a genetic test helped her make proactive decisions to protect her health. Jolie’s test revealed that she had a BRCA1 gene variant associated with higher breast cancer risk. She chose to have a preventive double mastectomy, reducing her breast cancer risk from 87% to 5%.¹
And Jolie isn’t the only one. Over the years, celebrities like Olivia Munn and Christina Applegate shared how genetic risk assessments helped them make decisions about preventive surgeries and cancer treatments.² ³
Guidelines recommend genetic testing for patients with several cancer types, including breast cancer,⁴ and for those whose personal or family history suggests hereditary cancer (where cancer risk gets passed down through a family’s genes).⁵ ⁶
Meanwhile, a growing body of research shows genetic testing beyond these guidelines could support comprehensive care, informing medical management strategies that may enable early detection and targeted prevention strategies for a broader range of cancers.
Two recent studies explore how genetic testing could impact risk-reducing measures for breast and ovarian cancers. Together, they show how genetic testing helps support patients’ preventive decisions about their health while avoiding overtreatment.
Genetic testing for breast cancer risk: Mexico study
Studies have found that Hispanic populations in the United States and Latin America tend to underutilize cancer prevention strategies.⁷ ⁸ In developed countries, the barriers to access have been reported as financial, medical and psychosocial (the mental, emotional, social and spiritual effects of a disease).⁹ ¹⁰
But little is known about what patients in Mexico think about genetic testing or how often families engage in cascade testing, a process where genetically related individuals pursue genetic testing to better understand their risks for hereditary conditions, like breast cancer.¹¹
A study of breast cancer patients in Mexico who have disease-causing (pathogenic) gene variants looked at how risk-reducing choices changed when a resource-constrained population gained better access to genetic testing.¹¹
The study surveyed carriers who received their genetic test results at least six months prior from two GCRA referral centers in Mexico.
It assessed:
- sociodemographic characteristics
- awareness of their genetic carrier status (and what that meant)
- whether or not they engaged in recommended risk-reducing measures
- whether their families started cascade genetic testing
- what barriers they faced
The results were encouraging.
Even in resource-constrained settings, when people know their genetic risk, they’re more likely to engage in lifestyle changes or treatments that reduce their risk of developing cancer. When carriers can take proactive measures for their health, the benefits can extend to at-risk relatives, which fosters a more informed and prepared community.
How cancer care changes–and doesn’t–when patients know their genetic makeup
When undergoing genetic testing, it’s common for patients to receive results that include variants of uncertain significance (VUS). These results aren’t positive or negative. Instead, they show that a patient has a gene variant that may or may not be clinically significant–we don’t yet know. So, a VUS result shouldn’t influence treatment or surveillance interventions.¹²
A new study examined almost 20,000 breast cancer patients who recently underwent genetic testing. It showed that patients who received a VUS result were not more likely than patients who received a negative result to undergo breast cancer-related therapies or surgeries (except certain chemotherapy drugs).¹²
This finding is significant because when patients and doctors received an uncertain result, they chose preventive therapies at the same rate as people who received negative results.
In other words, findings showed that VUS results don’t cause patients to pursue unnecessary and potentially expensive treatments beyond current guidelines.
“Over the years, there have been many discussions around preventive mastectomies and whether or not these measures have been overused in practice due to genetic testing results,” said Dr. Kevin Hughes, Director of Cancer Genetics at the Medical University of South Carolina Department of Surgery and an author of the study.
“When we found that the uptake of breast surgeries, particularly bilateral mastectomies, was comparable between patients with negative and VUS results in this large national cohort of patients with breast cancer, it confirmed our hypothesis that receipt of a VUS does not impact clinical management.”
The study also showed that when a patient received a positive genetic test result for a disease-causing variant, the patient was more likely to take risk-reducing measures, including bilateral mastectomies, chemotherapy and breast MRIs.
Why does this latest breast cancer research matter?
These two studies reaffirm the benefits of genetic testing while offering reassurance that receiving a VUS result doesn’t necessarily lead to overtreatment.
When patients discover their genetic risks, they aren’t the only ones who can benefit. Their family members can start cascade genetic testing to better understand if they, too, have a disease-causing variant and should consider preventive strategies.
With genetic testing, we can better understand genetic predispositions, clarify decisions about preventive measures, work to improve treatment plans, and ultimately develop more comprehensive cancer care for more people.
Invitae offers broad hereditary cancer panels that provide a holistic view. Order a test, get straightforward results and access expert support on the Invitae website.
References
- Jolie A. My medical choice. New York Times. May 14, 2023.
- Leake L. Olivia Munn was diagnosed with breast cancer 2 months after a normal mammogram. This is the tool she says ‘saved my life.’ Fortune. March 13, 2024. Accessed June 14, 2024.
- NBCF team. What celebrities have or have had breast cancer? National Breast Cancer Foundation, Inc. January 17, 2024. Accessed June 14, 2024.
- Kurian A, et al. JAMA. 2023;330(1):43–51.
- Genetic testing for inherited cancer risk. National Cancer Institute. April 8, 2024. Accessed June 14, 2024.
- Manahan ER, et al. Ann Surg Oncol. 2019;26(10):3025–3031.
- Chavarri-Guerra Y, et al. Cancer Res. 2018;78:P6–09–05.
- Weitzel JN, et al. Cancer Res. 2022;82:2214.
- Howard AF, et al. J Genet Couns. 2009;18(6):578–97.
- Padamsee TJ, et al. Breast Cancer Res. 2017;19(1):34.
- Mesa-Chavez F, et al. JCO Global Oncology. 2024;10:e2300417.
- Kurian A, et al. Journal of Clinical Oncology. 2024;42(16):10512–10512.
