Dr Kelly-Anne Phillips Discusses Hormonal Contraceptives, BRCA Mutations, and Breast Cancer Risk

Kelly-Anne Phillips, MBBS, MD, FRACP, FAHMS, founder of the Peter MacCallum Breast and Ovarian Cancer Risk Management Clinic, discussed research evaluating links between hormonal contraceptives and the risk of breast cancer for individuals carrying germline pathogenic variants in BRCA1 and BRCA2.

This transcript has been lightly edited for clarity and length.

Transcript

What were the key findings from your study on hormonal contraception and the impact on breast cancer risks in those with BRCA1 and BRCA2 mutations?

The key finding of this research was that BRCA1 mutation carriers have an increased risk of breast cancer if they've ever used hormonal contraception, and that increased risk is increased more for longer durations of use. So, more specifically, there was a 29% increase in the relative risk of breast cancer for BRCA1 carriers that have used hormonal contraception, with a proportional increase in risk of 3% per year of use.

How should these findings be translated into clinical practice or impact current guidelines for hormonal contraceptive use in this patient population?

Hormonal contraception is obviously an important health care option for women. It has risks and benefits for all women. So, I think that women need a personalized conversation about the use of hormonal contraceptives, particularly when they carry a BRCA1 mutation, really weighing up the increased risk of breast cancer that we've shown with the other benefits of hormonal contraceptives. And I think it's very important for us to try to provide women with individual absolute risk estimates rather than a more generic relative risk estimate, which is pretty hard for them to apply to their own situation. For example, if you extrapolate the results of our study, if you had a 20-year-old BRCA1 carrier who started hormonal contraception, and plans to use it for 10 years, her 10-year risk of breast cancer would increase from 3% to about 4%. So an absolute increased risk of only 1% over that 10 years. If she took it for 10 years, and you measure her 20-year breast cancer risk, we would estimate that would increase from 17% to about 22%. So that's a 5% increase in risk. These are the sorts of figures that we need to talk to our patients about rather than just providing them with relative risk estimates.

What further research is needed to deepen our understanding of the relationship between hormonal contraceptives, genetic mutations, and breast cancer risks?

Our study looked at all hormonal contraceptives combined, so that included the contraceptive pill, hormonal implants, and hormonal IUDs. And most of our data was really around oral contraceptives because that is mostly what women had taken. I think there is a much larger piece of research to be done regarding the individual types of hormonal contraceptives. I think, particularly, we need to understand better whether hormonal IUDs carry the same risk as the oral contraceptive pill, for example, because obviously that would be really important information for women if there were differences in the risks of breast cancer.