[Levonorgestrel-releasing intrauterine device (Mirena) and breast cancer: what do we learn from literature for clinical practice?].

Annual occurrence of breast cancer is constantly increasing in France. In 2000, the number of breast cancer cases for women of 30-49 years was estimated at 9,918, which represents 23.7% of all breast cancer cases diagnosed that year. The levonorgestrel-releasing intrauterine device (IUD LNG) is one of the most frequently used coils in France. Because contraception is an important matter for women whose ovarian function survived cancer treatments, the question of whether to use such device on a woman with breast cancer has become a frequent and controversial gynaecological issue. With the review of available literature as a basis, we have tried to answer the following questions. First, whether the use of IUD LNG increases the risk of breast cancer: there is at the moment no "A" level answer available. According to the only study published, which may be considered "C" level, there is no such increase. Second, whether the use of IUD LNG counterbalances the endometrial effects of Tamoxifene: based on a limited level of evidence via a single randomised controlled trial on a small number of patients for one year only, this device appears to be able to prevent benign endometrial modifications. However, there is no conclusive study regarding its effectiveness on the prevention of endometrium adenocarcinoma caused by Tamoxifene. In addition, there are numerous uncertainties as to whether levonorgestrel presence in the plasma would have a systemic prejudicial impact. Third, whether a woman with a personal antecedent of breast cancer can safely use DIU LNG: it is necessary to remove it promptly upon suspicion or diagnosis, to dissuade its use in case of current cancer, and, in the event of cancer remission for more than 5 years, to generally avoid this contraceptive method except on a case by case basis and with a regular medical follow-up. In the latter situation, the use of IUD LNG can be considered only after a multidisciplinary collective formal decision and after the woman gave her informed consent.