This is a pilot chemo-prevention study of the combination tamoxifen and 4-HPR in persons at increased risk of developing invasive breast cancer. The objectives of the study are to determine the acute and cumulative toxicity of tamoxifen and 4-HPR in high risk persons; to assess the feasibility of obtaining adequate tissue to study potential intermediate biomarkers of proliferative disease and malignancy using nipple aspiration, four quadrant fine needle aspirates, and breast core needle biopsies; and to study the effects of tamoxifen and 4-HPR on TGF-beta isoforms and the proliferative markers ki67 and PCNA pre- and post-therapy.