Hormonal contraceptive may up risk of breast cancer
Contemporary hormonal contraceptives appear to increase the risk of breast cancer, particularly in those with long durations of exposure, a recent study from Denmark has shown.
However, while the current study did not take into consideration additional breast cancer cases after the discontinuation of hormonal contraception, the absolute increase in risk is low, researchers said.
In 1,797,932 females without cancer or venous thromboembolism, there were 11,517 incident cases of breast cancer over a mean follow-up of 10.9±5.8 years. The current or recent use of any hormonal contraception significantly elevated the risk of breast cancer compared with never use (relative risk [RR], 1.20; 95 percent CI, 1.14–1.26; p=0.002). [N Engl J Med 2017;377:2228-2239]
Moreover, the duration of hormonal contraception had a significant effect on the risk of breast cancer (p=0.002), such that those with <1 year of use have lower risks (RR, 1.09; 0.96–1.23) than those with >10 years of use (RR, 1.38; 1.26–1.51).
Further stratification showed that the risk of breast cancer was only elevated in females with prolonged use (≥5 years), and that the increased risk persisted for at least 5 years after discontinuation of contraception (RR, 1.30; 1.06–1.58). In contrast, <5 years of exposure had no apparent impact on breast cancer risk.
“Our results suggest the rapid disappearance of excess risk of breast cancer after discontinuation of use among women who have used hormonal contraceptives for short periods, whereas the risk among women who have used these contraceptives for longer periods may persist for at least 5 years after discontinuation,” researchers said.
The age-standardized incidence rates of breast cancer for those with and without current or recent exposure to hormonal contraception were 55 and 58 events per 100,000 person-years, resulting in an age-adjusted risk difference of 3.
Despite the statistical link between the use of hormonal contraception in the past 6 months and the elevated risk of breast cancer, researchers said that, practically, the absolute increase in breast cancer cases as a result of hormonal contraception is low.
“[A]pproximately one extra breast cancer was diagnosed for every 7,690 women using hormonal contraception for 1 year… This risk should be weighed against important benefits of hormonal contraceptives such as good contraceptive efficacy and reduced risks of ovarian, endometrial, and perhaps colorectal cancer,” they added.