Women with atypical hyperplasia (AH) and lobular carcinoma in situ (LCIS) are at increased risk of breast cancer (BC) (~1-2 % per year). Over two decades ago, placebo-controlled randomized trials established that oral tamoxifen (20 mg/day) reduces breast cancer risk by 50% in generally defined high risk women, with ~70% reduction in women at high risk specifically due to atypical hyperplasia.[1] Years later, the side effects and toxicity of oral tamoxifen at 20 mg/day remain a significant barrier to its uptake and longterm compliance.[2, 3] To address the issue of toxicity, two main strategies have been pursued: 1) using a lower dose of oral tamoxifen, and 2) using a topical formulation of tamoxifen to avoid systemic side effects. The investigators will perform a prospective study of women with AH or LCIS who will take a short course of prevention therapy; breast tissue samples will be evaluated pre- and post-therapy to identify and evaluate very early biomarkers of response. The overall goal of the study is to evaluate short-term changes in background breast tissue induced by either low-dose oral tamoxifen or topical 4-OHT gel in women with AH or LCIS.
The investigators plan to prospectively study breast tissue changes after a short course of Tamoxifen (Tam).