Hormonal Birth Control Ups Breast Cancer Risk in Women With BRCA1 Mutations
Using any birth control that contains hormones increases the risk of breast cancer in women with a BRCA1 mutation, according to a study published in the Journal of Clinical Oncology. BRCA1 or BRCA2 mutation carriers already have a higher-than-average risk of breast cancer because of these mutations.
Key takeaways
Women with a BRCA1 mutation have up to a 72% risk of developing breast cancer by age 70. Using hormonal birth control increased this risk even more.
The researchers estimated that at age 58, a woman with a BRCA1 mutation who didn’t use hormonal birth control would have a 51.3% risk of developing breast cancer. If this same woman used hormonal birth control for 15 years, starting at age 18, she would have a 67.3% risk of developing breast cancer.
This includes birth control pills, patches, implants, injections, vaginal rings, and IUDs containing any hormones.
There was no increase in risk for women with a BRCA2 mutation who used hormonal birth control.
What the results mean for you
If you have a BRCA1 mutation and use hormonal birth control, it makes sense to ask your doctor about the risks and benefits of your birth control options. You may want to consider non-hormonal methods of birth control, such as non-hormonal IUDs, diaphragms, and condoms.
About the study
Research has consistently shown that women with a BRCA1 or BRCA2 mutation have up to a 72% risk of developing breast cancer during their lifetimes, with more than half of all breast cancers in these mutation carriers diagnosed when they’re younger than 50.
To figure out if hormonal birth control further increased the risk of breast cancer in these women, the researchers analyzed information from four earlier studies that included 3,882 women with a BRCA1 mutation and 1,509 women with a BRCA2 mutation.
Detailed results
About 53% of the BRCA1 carriers and 71% of the BRCA2 carriers had ever used hormonal birth control for at least a year. This includes birth control pills, patches, implants, injections, vaginal rings, and IUDs containing any hormones.
Half the women were followed for more than 5.6 years and half were followed for shorter periods of time.
During follow-up, 488 women with a BRCA1 mutation and 191 women with a BRCA2 mutation were diagnosed with breast cancer; 440 of the cancers in BRCA1 carriers and 151 cancers in BRCA2 carriers were invasive.
The researchers’ analysis found that any use of hormonal birth control was linked to a 29% relative increase in breast cancer risk in women with a BRCA1 mutation. This risk increased by 3% for each additional year of use.
There was no link between any hormonal birth control use and breast cancer risk in women with a BRCA2 mutation.
Absolute risk is your personal risk of developing breast cancer. The average woman’s risk is about 13%. Women with a BRCA1 mutation have up to a 72% risk of developing breast cancer.
Relative risk is how much something you do or something you’re exposed to changes that absolute risk.
To help women with a BRCA1 mutation understand how using hormonal birth control could increase their risk over time, the researchers estimated the absolute risk of breast cancer for an average woman with a BRCA1 mutation who started using hormonal birth control at age 18 and used it for 5, 10, or 15 years.
At age 58:
A woman who didn’t use hormonal birth control would have a 51.3% risk of developing breast cancer.
A woman who used hormonal birth control for 5 years would have a 56.6% risk of developing breast cancer.
A woman who used hormonal birth control for 10 years would have a 62% risk of developing breast cancer.
A woman who used hormonal birth control for 15 years would have a 67.3% risk of developing breast cancer.
As the researchers’ risk estimates show, using hormonal birth control for a shorter time may only cause a slight increase in your absolute risk. But using it for a longer time may cause an increase that you find unacceptable.
Phillips, Kelly-Anne, et al., Hormonal Contraception and Breast Cancer Risk for Carriers of Germline Mutations in BRCA1 and BRCA2. JCO. Published online Oct. 2, 2024.
— Last updated on February 6, 2025 at 6:49 PM