Premenopausal women who use a hormone-releasing intrauterine device, such as the Mirena IUD, are at greater risk of developing breast cancer, according to a study recently published in the journal Obstetrics & Gynecology.
There are three IUDs marketed in the United States – the ParaGard, Mirena and Skyla. Only Mirena and Skyla, which are both made by Bayer Healthcare, contain a small amount of the levonorgestrel, a synthetic form of the hormone progestin. IUDs are used to prevent pregnancy, but levonorgestrel-releasing IUDs can reduce heavy bleeding and are often given to women to help treat heavy periods, a condition known as menorrhagia, as well as endometriosis and chronic pelvic pain.
Researchers from the Department of Obstetrics and Gynecology at the Hyvinkaa Hospital in Finland conducted the study to examine cancer rates among premenopausal women using levonorgestrel-releasing IUDs. The study involved more than 93,000 women between the ages of 30 and 49, all of whom were using levonorgestrel-releasing IUDs to treat heavy menstrual bleeding.
Researchers found that over time, the IUD did not significantly raise the risk of cancers in the uterus, ovaries, pancreas, or lungs. However, they did see a 19 percent increased risk in breast cancer cases, especially among women between the ages of 45 and 49 compared to women who did not have this type of IUD.
Researchers said further study is needed to rule out other factors that could contribute to the increased risk of breast cancer, such as whether women who suffer from heavy periods may be at greater risk of cancer.
Bayer is already facing several lawsuits in the United States alleging the company’s Mirena IUD caused injuries, and that Bayer did not adequately warn women of the risks. The injuries involve migration of the device from its intended location. In some cases the device has perforated organs, and surgery is often needed to remove the device.