Development of a Quantitative Tissue Optical Index of Breast Density

The goal of this study is to develop a safe, painless imaging method to measure the change in breast density caused by hormonal chemotherapy treatments such as tamoxifen. For many patients with breast cancer, chemoprevention drugs (such as tamoxifen) can reduce the risk of recurrence. However, tamoxifen can also cause serious side effects such as blood clots and an increased risk of uterine cancer. Patients would benefit from an individualized method of determining whether the chemoprevention is working. Recent studies have shown that a course of tamoxifen is more effective at reducing risk in women who exhibit >10% reduction in breast density compared to women who had little or no density change. The study suggests that breast density is a predictor of the effectiveness of tamoxifen. We propose to use an imaging method that uses safe visible and near-infrared light to measure breast tissue called diffuse optical spectroscopic imaging. Diffuse optical spectroscopic imaging allows patients to be followed through treatment with a cost-effective, bedside, handheld scanning probe. In this study, we will examine whether diffuse optical spectroscopic imaging is sensitive to the density changes induced by tamoxifen as a preventative hormonal chemotherapy agent. MRI will be used as the standard for comparison. We expect to discover that after 12-18 months, women on tamoxifen treatment will show a significant reduction in breast density compared to women not taking tamoxifen, and this change can be monitored using DOSI alone. If validated, our method could be used to determine if tamoxifen treatment is working in an individual patient and could guide doctors about the decision to end and/or switch to a different treatment. In addition, a validated index of density that can be obtained using an inexpensive, risk-free bedside technology could be applied to the challenging problem of measuring individual risk of breast cancer in the broader population.