By Jaimie Roebuck
Women with a BRCA1 or BRCA2 genetic mutation are at higher risk of developing breast and ovarian cancer. Dr. Joanne Kotsopoulos, scientist at Women’s College Research Institute, is investigating these hereditary cancers at the genetic level to deliver evidence-based, personalized strategies to improve women’s health and lower cancer incidence and mortality rates around the world.
In her most recent paper, Oral Contraceptives and BRCA Cancer: A Balancing Act, published in JNCI: Journal of the National Cancer Institute, she looks at the impact of modifiable exposures on cancer risk, particularly oral contraceptives and hormone replacement therapy (HRT). They contain similar hormone profiles, but the doses tend to be much higher in oral contraceptive preparations.
Dr. Kotsopoulos explores whether oral contraceptives increase or decrease the lifetime risk of developing cancer in BRCA carriers. The answer? It depends. For a woman who elects to have both breasts surgically removed (known as preventive bilateral mastectomy) there is no downside to taking an oral contraceptive with regards to her cancer risk. For a woman with two breasts intact and an oophorectomy (surgical removal of one or both ovaries), there is an increase in her breast cancer risk. However, we have to ask whether the increase in risk warrants consideration of a different form of contraception.
This question is particularly important for a young woman who has just recently discovered she is carrying a BRCA1 or BRCA2 mutation and is considering oral contraceptives for the purpose of birth control. Her decision to take the pill or not is likely made well before she is a candidate for preventive surgery, and it may be unsettling to ask her to consider options for preventive surgeries so well in advance. In some cases, young women may seek genetic testing for the sake of knowing if the pill is safe or is best avoided. Understanding the impact of newer forms of contraception, including injectable, implants and intrauterine devices, will be important given their increasing popularity among women of reproductive age.
Dr. Kotsopoulos also highlights the impact of HRT use after oophorectomy on the incidence of breast cancer. These elevated risks are likely to be real given the well-described impact of progesterone signaling on breast cancer risk in women with a BRCA1 mutation. This represents a pressing concern given the need to manage symptoms attributed to early surgical menopause.
These are all important topics for discussion and these questions are sure to come up more frequently in sessions with genetic counsellors and with other health-care providers.