Most women are nervous about using a new form of contraception, especially when it involves added hormones– and who can blame us? Everywhere we look, it seems like a new study is revealing long-term risks associated with popular birth control measures. If you are interested in using a Mirena IUD, a low-hormone birth control option that sits inside the uterus, you may be concerned that it can increase the risk of cancer or other long-term illnesses.
There is really no evidence that the Mirena IUD increases cancer risk. In fact, there is some (albeit limited) evidence that it may decrease the risk of cancer. Here’s a run-down of the evidence.
A comprehensive investigation by the Food and Drug Administration found that it is unlikely that the Mirena IUD could increase a person’s cancer risk. It does not contain any drugs, hormones or compounds known to contribute to the formation or growth of cancerous cells. On the other hand, birth control methods containing estrogen have been theoretically implicated as a potential contributing factor to some cancers.
Reasons for Low Risk
The Mirena IUD contains very low levels of reproductive hormones, because it sits directly inside the uterus, where miniscule amounts of progestin perform the same functional effect as a systemic birth control pill. It does not contain any estrogen and fairly low amounts are absorbed into the bloodstream. There are no known or suspected carcinogens in the other materials found inside a Mirena IUD, so it is very unlikely that it could cause cancer.
A review by the International Agency for Research on Cancer, or IARC, suggested that birth control containing only progestin may decrease the risk of endometrial cancer– a form of cancerous growth occurring in the lining of the uterus. In theory, it could also decrease the risk of ovarian or uterine cancers, but more studies need to take place to confirm these results.
Unfortunately, the only conclusive way to demonstrate a product’s safety is to examine its effect on cancer rates over the course of several decades. Because the Mirena IUD has only existed for about 20 years, it is impossible to conclusively prove that it does or does not increase a person’s risk of developing cancer. Only time will tell if women who have used the Mirena IUD experience a significantly higher or lower cancer rate than those using other birth control techniques.
Exceptions to the Rule
Although there is almost no evidence that the Mirena IUD increases the risk of breast cancer, most physicians advise women with breast cancer to forgo any hormonal contraception while undergoing treatment. Others also suggest that they avoid hormonal methods of birth control for an indefinite period of time. Until more is known about the effects of the Mirena IUD on breast cancer growth, it is best avoided by inviiduals who have, or have had, this condition.
IARC- Hormonal Contraceptives, Progestogens Only
FDA- Mirena Pharmacology Review