Some hormonal contraceptives linked to increased breast cancer risk

Some hormonal contraceptives carry a slightly higher breast cancer risk than others, with desogestrel linked to greater increases than alternative products.

A study of more than two million Swedish women and teenage girls found that the risks vary depending on the type of hormone used in contraceptive methods.

Researchers tracked women aged 13 to 49 through national registers from 2006 to 2019 to assess how different contraceptives affect breast cancer risk.

The work, by Uppsala University and SciLifeLab, represents the largest study of its kind.

Overall, hormonal contraceptive use was linked to a 24 per cent increased risk of breast cancer — equivalent to about one extra case per 7,800 users each year.

The risk also rose with longer use.

Professor Åsa Johansson is research group leader at Uppsala University and SciLifeLab and the study’s senior author.

Th researcher said: “Not all hormonal contraceptives have the same effect on the risk of breast cancer.

“Our results indicate that some progestins – particularly desogestrel – are linked to a higher risk of breast cancer, while others, such as depot medroxyprogesterone acetate injections, showed no increase.”

The study showed that both combined contraceptive pills and hormonal intrauterine coils containing levonorgestrel — among the most commonly used products in Sweden — were associated with lower risk than desogestrel.

Desogestrel is a synthetic version of progesterone, known as a progestin, used in mini-pills and some combined pills.

Long-term use of desogestrel products for five to ten years was associated with almost 50 per cent higher risk.

By contrast, levonorgestrel products — another type of progestin used in pills and hormonal intrauterine devices (IUDs) — were linked to less than 20 per cent higher risk with long-term use.

Combined pills containing drospirenone and oestrogen were not linked to an increased risk of breast cancer.

The study drew on Sweden’s national registers, which include all dispensed prescriptions and cancer diagnoses.

As progestin-only methods become increasingly popular alternatives to traditional combined pills, understanding their long-term health impact is becoming more important.

“Hormonal contraceptives are highly effective and provide important health benefits, and we do not encourage women to stop using them,” said Fatemeh Hadizadeh, the study’s lead author.

“In addition to preventing unwanted pregnancies, they reduce the risk of ovarian and endometrial cancer, relieve menstrual pain and heavy bleeding, help with acne, and give women greater control over their reproductive health.

“At the same time, breast cancer is the most common cancer among women and until better preventive treatments are available, avoiding drugs that increase the risk can make a big difference – especially for women who are already at higher risk.

“The results of our study provide doctors and women with useful information to act on.”