Breast cancer is one of the most common types of cancer worldwide, with around 2.3 million women diagnosed with the disease every year. In the UK alone, it is estimated that one in seven women will develop breast cancer at some point in their lifetime.
Until now, it was thought that only the combined hormonal pill carried a greater risk of breast cancer. But a recent study suggests that the progestogen-only pill and other forms of hormonal contraception also carry the same increase in breast cancer risk as the combined pill. The study found women who used progestogen-only hormonal contraceptives had between a 20-30% greater risk of developing breast cancer compared to women not using these methods. This increased risk disappeared ten years after stopping the method.
If we were to look at women aged 50-54, we know from other research that about 280 women per 100,000 are diagnosed with breast cancer each year. If birth control increases breast cancer risk by 20-30%, it would mean an additional 70 women per 100,000 would develop breast cancer each year. But one of the difficulties of deciding on whether a contraceptive method presents an acceptable risk is that many other common lifestyle behaviours also increase cancer risk. For example, it’s estimated that while 1% of breast cancers in the UK are caused by hormonal contraceptives, 5% are caused by not breastfeeding, 8% by being overweight and 8% by drinking alcohol.