Chemoprevention studies are long and expensive. Gaining information about the feasibility of an agent using biomarker endpoints can save money and ensure that only the most promising agents move forward. There is strong evidence to suggest breast cancer prevention properties for vitamin D. The safety and tolerability of this agent makes it a perfect candidate for a chemopreventive agent. This clinical trial will evaluate the effect of vitamin d on several breast cancer; providing important information regarding the feasibility of a larger chemoprevention study using cancer development as the endpoint. Successful completion of this study will also validate this design of biomarker testing of potential chemoprevention agents within a cooperative group setting and add to data validating these specific biomarkers.

Methods: This is a randomized placebo controlled trial of one year of 2000 units of vitamin D (cholecalciferol) for premenopausal women (≥ 35 years) with increased breast density. The primary aim of this study is to evaluate the effect of vitamin D on breast density. Secondary aims include evaluation of vitamin D effects on IGF1 and markers of cellular proliferation (Ki-67 and atypia). In addition 3 methods of density analysis (Breast Imaging Reporting and Data System (BI-RADS), Visual Analogue Scale (VAS), and the Boyd method) will be compared. For the primary endpoint of change in mammographic density we will have an 87% power to detect a standardized effect size (difference in means divided by standard deviation) of 0.4 in change of mammographic density between two arms. The target effect size is 2.64%.This study was activated 10/15/2010 and has been opened at 75 sites with 15 patients enrolled. Target accrual is 250.

Funding: This study is sponsored by the NCI and CALGB.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr OT2-04-01.