Hormonal contraceptives come with an increased risk of breast cancer, according to a new study conducted by researchers from the University of Oxford.
The study, published in PLOS Medicine on Tuesday, showed an increased risk of around 20-30% in breast cancer linked to current or even recent use of hormonal birth control pills, including combined oestrogen and progestogen birth control pills and progestagen-only contraceptives.
The study’s abstract said the findings show that “current or recent use of progestagen-only contraceptives is associated with a slight increase in breast cancer risk,” which is “similar in magnitude to that associated with combined hormonal contraceptives.” Notably, progestagen-only contraceptive use has substantially increased in recent years.
Researchers also found that the risk of breast cancer in pre-menopausal women taking these forms of birth control increased with age. “Given that the underlying risk of breast cancer increases with advancing age, the absolute excess risk associated with use of either type of oral contraceptive is estimated to be smaller in women who use it at younger rather than at older ages,” the paper said.
The new findings, combined with past research on hormonal contraceptives, “suggest that the 15-year absolute excess risk of breast cancer associated with use of oral contraceptives ranges from 8 per 100,000 users for use from age 16 to 20 to about 265 per 100,000 users for use from age 35 to 39.”
This heightened risk is found to gradually decrease in the years after women stop taking the contraceptives.