National Cancer Institute (NCI)
This phase II trial evaluates response-guided low-dose tamoxifen for reducing breast density in women who are at higher than average risk for breast cancer. Increasing breast density is a well established risk factor for breast cancer. Tamoxifen is a selective estrogen receptor modulator. It works by blocking the effects of the hormone estrogen in the breast. Tamoxifen has been shown to reduce breast density, even at reduced dosages, and is approved for the prevention of breast cancer.
PRIMARY OBJECTIVE: I. To evaluate whether the overall proportion of premenopausal tamoxifen responders (defined by absolute dense area reduction on mammogram of \> 10%) can be increased through a strategy of within-individual dose escalation among non-responders from 5 mg per day to 10 mg per day. SECONDARY OBJECTIVES: I. To assess the association of plasma levels of major tamoxifen metabolites with tamoxifen dose and breast density changes from baseline. II. To evaluate longitudinal change from baseline in serum biomarkers of tamoxifen response at each dose level: sex hormone binding glob…
Inclusion Criteria: * Premenopausal women at the time of enrollment defined by any of the following: * Age under 50 years and regular menstruation (most recent period within the past 3 months) * Age under 50 years and continuous hormonal contraception use and at least one intact ovary * Women who are not postmenopausal based on serum hormone levels. Women with estradiol \> 30 pg/mL and follicle-stimulating hormone (FSH) \< 30 IU/mL are eligible * Women with any of the following: * A history of unilateral estrogen receptor (ER) positive ductal carcinoma in situ (DCIS) with local ther…
Undergo biopsy
Undergo collection of blood samples
Undergo mammography
Ancillary studies
Given PO