LNG-IUD and breast cancer: Number 2 – 2026

Key points• Breast cancer is the most common type of cancer among women worldwide.• There is concern regarding the use of hormonal contraceptives and their possible relationship with the risk of breast cancer.• Several studies have evaluated the association between hormonal contraceptives and breast cancer, achieving heterogeneous results.• Some observational studies and systematic reviews suggest an association between levonorgestrel intrauterine device (LNG-IUD) use and breast cancer.However, these findings are limited by confounding factors and methodological weaknesses in the studies.• When observed, the increased risk of breast cancer associated with LNG-IUD use is small in absolute terms (occurrence of 1 to 14 additional cases of breast cancer in every 10,000 users of the method) and should be interpreted considering the contraceptive and therapeutic benefits of the method. Recommendations• Breast cancer is a highly prevalent and hormone-dependent disease, which justifies clinical and social concern regarding the use of hormonal contraceptive methods in women of reproductive age.• Currently available scientific evidence does not consistently and robustly demonstrate a clinically significant increase in the risk of breast cancer associated with LNG-IUD use in the general population.• The observational studies suggesting a possible association between LNG-IUD and breast cancer present heterogeneous results and have important methodological limitations, especially regarding the inadequate control of confounding factors.• When identified, the increased risk is small in absolute terms (occurrence of 1 to 14 additional cases of breast cancer in every 10,000 users of the method) and should be interpreted in light of the contraceptive and therapeutic benefits of LNG-IUD use, including high contraceptive efficacy, reduction of uterine bleeding, and protection against endometrial cancer.• Prescription of the LNG-IUD should be accompanied by evidence-based, clear counseling, considering the patient's clinical, reproductive, and psychosocial context.• Adopting these recommendations ensures safe clinical practices, prevents unfounded alarmism, and promotes equitable access to effective contraception, thereby fostering a positive impact on both women's reproductive health and society.