Women on hormonal contraception are 20 to 30 per cent more likely to get breast cancer, according to a new study.

But cancer charities have said “the risk is small”.

Let’s take a look.

What is the link between hormonal contraception and breast cancer?

It’s been known for some time that “combined” contraception – which uses the hormones oestrogen and progesterone – is linked to an increased risk of breast cancer.

This latest study, published in the journal PLOS Medicine, has shone a light on progesterone-only contraception, including the so-called “mini pill”, which you can get from pharmacies without a prescription.

The researchers found that current or recent use of progestogen-only contraceptives increased a woman’s chance of developing breast cancer within the next 15 years by 20 to 30 per cent, depending on how old a woman was at the time. This is on a par with what’s already known about the risks associated with combined contraception.

The increased risk was found to be roughly the same whether hormonal contraception was taken as a pill, IUD, implant or injection.

Oxford University researchers looked at nearly 30,000 patient records held by family doctors based on routinely collected data that covers about 7 per cent of the UK population, but is broadly representative of the UK in regards to age, sex and ethnicity.

The overall risk of breast cancer remains low

That headline figure of an increase in risk of 20 to 30 per cent sounds scary. But it’s important to be clear about what the stat actually tells us.

It doesn’t mean that 20 to 30 per cent of women on the pill will get breast cancer as a result. It means that hormonal contraception use might increase your already low risk of breast cancer by 20 to 30 per cent, compared to the risk you started with.

For example, for every 100,000 women on the pill in their late teens, the researchers would expect an extra eight cases of breast cancer. The figure for women in their late 30s is 265 extra cases per 100,000 taking hormonal contraception.

Senior Health Information Manager at Cancer Research UK, Claire Knight, said that combined and progestogen-only hormonal contraception “can increase the risk of breast cancer”, but “the risk is small”.

And she noted that women who are most likely to be using contraception are under the age of 50, “where the risk of breast cancer is even lower”.

Ms Knight also added that there are “lots of possible benefits” of using contraception.

According to the NHS, the combined pill can also decrease the risk of developing other cancers such as womb (uterus) cancer, ovarian cancer and bowel cancer.

For anyone looking to lower their cancer risk, “not smoking, eating a healthy balanced diet, drinking less alcohol, and keeping a healthy weight will have the most impact,” Ms Knight added.

Dr Kotryna Temcinaite, Head of Research Communications at charity Breast Cancer Now, said “a slight increase in risk during the time a woman uses hormonal contraceptives means only a small number of extra cases of the disease are diagnosed”.

However, she noted that the study didn’t look at what hormonal contraceptives the women may have used in the past, take into consideration how long they may have been on the progestogen-only contraception, and didn’t factor in whether a family history of the disease contributed to their level of risk.
Dr Temcinaite added: “Further work is needed to help us fully understand the impact of using this type of contraception.”