Oral Contraceptives and Risk of Breast Cancer
Posted: Friday, January 15, 2021
A recent study, published in Cancer Research, suggests that women who use oral contraceptives seem to have a slightly increased risk of breast cancer, although the effects appeared to be limited to a few years after discontinuing their use. However, women who use oral contraceptives may have a lower risk of developing ovarian and endometrial cancers than women who do not, even decades after discontinuing their use. The research explored a longer follow-up than in previous studies, demonstrating that the protective effect of these agents may last up to 35 years after their discontinuation.
“Our results enable women and physicians to make more informed decisions considering oral contraceptive use, thus constituting an important step towards personalized medicine,” Åsa Johansson, PhD, of Uppsala University, Sweden, and colleagues, reported.
The study team conducted an observational study including more than 256,000 women from the UK Biobank, a large cross-sectional cohort that was established to improve prevention, diagnosis, and treatment of a wide range of diseases. Cancer diagnoses were collected using self-reported data from national registers until March 2019. Cumulative risk and instantaneous risk of cancer were measured by odds ratio (OR) and hazard ratio (HR), respectively.
Increased odds of breast cancer were observed for women who used oral contraceptives when limiting the follow-up to 55 years of age (OR = 1.10). A higher hazard ratio associated with breast cancer was found only in former users less than 2 years after discontinuation of oral contraceptives (HR = 1.55). The odds of developing ovarian cancer (OR = .72) and endometrial cancer (OR = .68) were lower among women who used oral contraceptives than those who did not; and the association was stronger with longer use (P < .001).
“Given the body of evidence presented in our study, oral contraceptives can dramatically reduce women’s risk of ovarian and endometrial cancer, whereas their effect on lifetime risk of breast cancer is limited,” the research team concluded.
Disclosure: The authors reported no conflicts of interest.
