Dear Dellalulu: Atypical ductal hyperplasia (ADH) is a risk factor for developing breast cancer. It does not mean that breast cancer will develop, only that the woman's relative risk of developing breast cancer in her lifetime is higher than average. There have been studies demonstrating that tamoxifen can significantly reduce the risk of developing breast cancer by as much as 49% in women who are at high risk. Obviously, this is also a personal decision as well - balancing risks against benefits. Another option may be to seek a second opinion (preferrably from a breast specialist) as it may help you to gather more information so that you can make the best decision for you.