July 28, 2014 — Researchers have found a 20% increased risk of breast cancer associated with levonorgestrel-releasing contraceptives, such as Mirena, an intrauterine device (IUD).
The study, published in Obstetrics & Gynecology, tracked nearly 94,000 women from Finland between the ages of 30-49 who used a between 1994 and 2007. All of the women were using an IUD to treat heavy menstrual bleeding (menorrhagia).
During the study, a total of 2,781 cases of cancer were detected. Levonorgestrel-releasing IUDs were associated with a higher risk of breast cancer than the general Finnnish population, but a much lower risk of certain types of cancer:
- endometrial cancer risk was 50% lower
- ovarian cancer risk was 40% lower
- pancreatic cancer risk was 50% lower
- lung cancer risk was 32% lower
Researchers concluded that levonorgestrel-releasing IUDs might have a protective effect against certain cancers. Even so, the possible risk of breast cancer adds to a number of troubling side effects associated with Mirena.
What is the problem?
Bayer, the manufacturer of Mirena, is facing about 2,000 lawsuits from women who were injured when the IUD spontaneously migrated out of position, perforated the uterus, and had to be removed surgically. In some cases, women were misdiagnosed for years because doctors were unaware of the side effect and assume it had simply fallen out.
Since 2008, the FDA has received about 5,000 reports indicating that Mirena can spontaneously move out of place. Members of the litigation accuse Bayer of downplaying this risk information, putting public safety at risk.