Study Shows Mirena IUDs Connected to Breast Cancer

Merina IUDA recent study published in the Obstetrics & Gynecology medical journal researched the connection between certain intrauterine devices (IUDs) and a higher risk of breast cancer. This study specifically focused on women who used Mirena, sold by Bayer, and similar IUDs that release a synthetic progestin known as levonorgestrel to prevent pregnancy and treat heavy periods. The small, plastic, T-shaped device is placed in the uterus to partially suppress ovulation and thin the uterine lining to prevent implantation of a fertilized egg.

This study collected data from over 93,000 women between the ages of 30 and 49 who used Mirena or other IUDs that release levonorgestrel from 1994 to 2007. All of the patients chose this form of treatment for menorrhagia, a medical term for heavy and prolonged menstrual bleeding.

Of the women in the study, 2,781 patients received breast cancer diagnoses. In the case of breast cancer specifically, there were 1,542 cases, as opposed to the calculated normal incidence rate of approximately 1,292 breast cancer diagnoses. When applied to the population as a whole, this would account for a 20% increased risk of breast cancer for patients using Mirena.

Although breast cancer risk appears to increase while on Mirena, the risk for some other cancers seems to get lower when using these devices. Endometrial adenocarcinoma and pancreatic cancer decreased by 50%, diagnostic rates of lung cancer decreased by 32%, and ovarian cancer rates decreased by 60%.

“Using the levonorgestrel-releasing intrauterine system for treatment of menorrhagia during reproductive years was associated with a lower incidence of endometrial, ovarian, pancreatic, and lung cancers than expected,” stated the research authors. However, they did mention the need for more testing to establish the influence of other factors, such as lifestyle and genetics.

Patient Education Is Key

Any form of medical treatment carries risks. While there are benefits to using IUDs, there are also serious risks, including the 20% increased risk for breast cancer. Mirena has also been reported to include side effects such as spontaneous migration of the device and perforation of the uterus. Patient advocates suggest that more comprehensive patient education initiatives to fully inform patients of the serious risks associated with IUD use would benefit women.

Dr. Angela Marshall, the director of Comprehensive Women’s Health in Silver Spring, Maryland, stated, “We need to educate our patients, because many of these therapies may work, but some could have serious side effects. Women need to be told. Then it’s up to the patient, along with a doctor’s guidance, to make the decision.” Better patient information upfront could allow women to make smarter, well-informed decisions about their health.