Breast cancer risk differs between types of hormonal contraceptives
A new study from Uppsala University shows that the risk of breast cancer varies between different types of hormonal contraceptives. Researchers followed more than two million women and girls aged 13–49 across Sweden between 2006 and 2019, using national health registers to compare how different hormonal methods influence cancer risk over time.
The study was led by Åsa Johansson, SciLifeLab Group Leader and Professor at Uppsala University, who served as the senior author, with Fatemeh Hadizadeh from Uppsala University as the first author.
Results revealed that contraceptives containing desogestrel were linked to the highest increase in breast cancer risk, while depot medroxyprogesterone acetate injections showed no elevated risk. Commonly used methods such as combined oral contraceptives and hormonal IUDs with levonorgestrel were associated with lower risk compared with desogestrel-based products. Overall, hormonal contraceptive use was tied to a 24% higher relative risk of breast cancer — about one additional case per 7,800 users per year — and the risk increased with longer duration of use.
The researchers emphasize that hormonal contraceptives remain highly effective and offer several health benefits, including protection against ovarian and endometrial cancers, relief from menstrual pain, and greater reproductive control. However, the findings underline the importance of choosing the right product, particularly for women with an elevated baseline risk of breast cancer.
The study also highlights the power of Sweden’s unique national health data, which makes it possible to conduct large-scale population studies that reveal even small differences in disease risk between medical treatments.
“Sweden has unique opportunities for health research thanks to the ability to link individuals through personal identification numbers. Prescription drug registers, which contain all dispensed prescriptions, can be linked to health outcomes, giving researchers the opportunity to study the long-term effects of treatments in everyday clinical practice. For many marketed drugs, the clinical evidence regarding long-term effects is still insufficient to fully guide physicians and policymakers. By using such health data, we can fill this knowledge gap and evaluate both the relative effectiveness of treatments and their potential long-term side effects. Together with the other Nordic countries, and with Sweden’s large datasets, this offers a unique opportunity for research that can improve patient care.” Says Åsa Johansson.
DOI: 10.1001/jamaoncol.2025.4480
Learn more in the Uppsala University press release
Photo of Åsa Johansson: Mikael Wallerstedt.
Photo of Fatemeh Hadizadeh: Arash Hadadgar.
