The purpose of this study is to see if Vagifem® 10mcg is safe for women who have had breast cancer. Vagifem is an estrogen product. It is a tiny tablet that is inserted into the vagina. It relieves vaginal dryness. Women who have had breast cancer are usually told not to take estrogen. This is because estrogen use can lead to a breast cancer recurrence or a new primary breast cancer. It is unclear if the estrogen in Vagifem is only absorbed in the vagina. It may be absorbed into the blood stream for a short time and may cause a brief rise in your estrogen level. However, there is no clear evidence that this would cause any bad effects in patients with breast cancer. How much, if any, of these topical estrogens are absorbed through the vagina is not known. We also do not know what the impact is of low dose estrogen absorption on breast cancer outcomes. Also, the absorption should decrease as the mucus membranes are restored after estrogen exposure.