CONTRACEPTIVE pills increase the risk of breast cancer by up to 30 per cent, a study found.
The added risk is still tiny — less than 0.3 per cent — but above average for users of the newer progestogen-only “mini pill” as well as those who take the older combined pill.
Contraceptive pills increase the risky of breast cancer between 20 and 30 per cent, a study by Oxford University found
Oxford University scientists said the risks were substantially higher in older women than those in their teens and 20s.
While the chances of developing cancer on the combined contraceptive were well-known, the new research provides fresh insight into the newer pill.
Study author Kirstin Pirie said the risks should be weighed against the “well-established benefits” of contraception.
She said: “All types of progestogen-only contraceptives are associated with a slight increase in breast cancer risk, similar to that of combined oral contraceptives.
“Absolute excess risk associated with use of either type of oral contraceptive will be smaller in women who use it at younger rather than at older ages.”
Around 27 per cent of women were prescribed contraceptive pills by NHS Sexual and Reproductive Health Services in 2021/22.
Separate studies show the proportion of women taking progestogen-only pills increased from 4.3 per cent in 2000 to 10.8 per cent in 2018 in the UK.
During the same period, the figure fell from 26.2 per cent to 14.3 per cent for combined hormonal contraception.
The combined pill uses two hormones — oestrogen and progesterone — to stop the ovaries releasing an egg each month, and is 99.7 per cent effective against pregnancy.
In contrast, the progestogen-only pill only contains one hormone and causes cervical mucus to thicken, preventing sperm from entering the womb, with a similar level of effectiveness.
Both pills can cause a variety of side effects, including tender breasts and feeling sick, and can also affect body weight, mood and libido in some women.
Doctors may discourage combined pills if you have a history of breast cancer.
The link between the pill and the disease is poorly understood, but the hormones used in them have been shown to increase the risk of some breast cancers.
The latest study, published in PLOS Medicine, compared how the two pills impact the risk of the disease.
Researchers tracked contraceptive use in nearly 10,000 under-50s with breast cancer from 1996 to 2017.
They were compared to just over 18,000 disease-free women.
Women taking either pill were between 20 to 30 per cent more likely to develop breast cancer.
Using either for five years increased cases by 8 per 100,000 for women aged 16 to 20 and 265 per 100,00 for 35- to 39-year-olds.
Dr Kotryna Temcinaite, of Breast Cancer Now, said: “There is a small increased risk of developing breast cancer for women while they are using a progesterone-only contraceptive.
“For both types of contraceptives, if you stop using them, this added risk of breast cancer reduces over time.”
She added: “Breast cancer is rare in young women.
“A slight increase in risk during the time a woman uses hormonal contraceptive means only a small number of extra cases of the disease are diagnosed.”
