Breast cancer will develop in one of eight women in the United States. Although screening mammography has made early detection of breast cancer possible, many women continue to have breast cancers that are not apparent by mammography. It is well known that early detection of breast cancer can be lifesaving. This study is designed to examine protein molecules secreted in body fluids that may be useful in detecting early breast cancer. Since nipple aspirate fluid, among other types of fluid, is collected, only women with breast(s) are eligible to participate.