According to the Centers for Disease Control and Prevention, 99 percent of sexually active women from 2006 to 2010 used at least one contraceptive method at some point. For many women, that method is the IUD - or intrauterine device.  It was once thought to have minimal risks, but a new study has found that certain forms of IUD may actually put women at higher risk for breast cancer.

The study looked at the levonorgestrel-releasing intrauterine system (LNG-IUS) or progesterone-releasing IUD.  This IUD is used as a contraceptive and also to treat women who suffer from heavy periods, endometriosis, and chronic pelvic pain.  

Finnish researchers from the Department of Obstetrics and Gynecology at the Hyvinkää Hospital in Hyvinkää, Finland, wanted to examine this form of IUD and its association with various cancer rates.  For the study, researchers followed more than 93,000 Finnish women between the ages of 30 and 49 who were using the IUD to treat their heavy periods from 1994 to 2007.

Investigators did not find any link between the use of this device and cancers of the uterus, ovaries, pancreas, or lungs.  But they did see a rise in the number of breast cancer cases, especially in women between the ages of 45-49, compared to women in the general Finnish population who were not using this particular IUD.

"The number of diagnosed new breast cancer cases among Finnish women who used LNG-IUS for menorrhagia was 19 percent higher than in Finnish general population," commented Dr. Tuuli Soini, the lead author of the study.

It's possible that the women who were using this form of IUD to treat their heavy periods were predisposed to breast cancer as a complication of their condition.  Or that another cause was responsible for the increase.  But it's also possible that this form of IUD could increase breast cancer risk.  

And that, notes researchers, is something that both doctors and their patients should know about.

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