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    Research Grants Awarded

    Breast Sound Speed: A Potential Predictor of Breast Cancer Risk

    Study Section:
    Risk and Prevention, Epidemiology

    Scientific Abstract:
    In 1976, Wolfe discovered that the relative risk of developing breast cancer was dependent on breast density. Since then, numerous studies have shown that women with high mammographic percent density are at 4- to 7-fold increased risk of developing breast cancer compared to women with fatty breasts1. Although breast density is a moderate to strong risk factor for developing breast cancer, no risk assessment models currently include breast density. The reliance on mammography to measure breast density has prevented widespread adoption of breast density as a risk factor. For example, tracking breast density under various conditions and times (e.g., phase of menstrual cycle) would lead to unnecessary exposure to ionizing radiation. Furthermore, it is ironic and unfortunate that mammographic sensitivity for cancer detection markedly deteriorates with increased breast density. We define the current gap in the knowledge base as ?the inability to develop a safe and efficient risk assessment tool based on breast density measurements that also offers alternative detection of cancers missed by mammography in dense breasts?. We propose to bridge the gap in the knowledge base by using transmission ultrasound to assess sound speed as a measure of breast density. Our preliminary studies suggest that the average breast sound speed correlates with mammographic percent density. The objective of this proposal is to confirm these preliminary results through more precise phantom measurements and by improving the accuracy and accrual to our in-vivo study. The central hypothesis of this study is that the average acoustic sound speed of the breast is a measure of breast density. We will test this hypothesis through experiments guided by the following specific aims. - Confirm the relationship between in vitro breast density and sound speed - Confirm the relationship between in-vivo sound speed and mammographic percent density - Assess role of sound speed in evaluating breast cancer risk under different trial conditions Phantom measurements will be used to establish the functional relationship between density and sound speed. A cohort of 150 new patients will provide data to establish the in-vivo relationship between sound speed and mammographic percent density. A subset of patients will be called back to assess the role of confounding factors such as varying breast density during the menstrual cycle. A demonstration of sound speed as an independent marker of breast density would enable the larger in-vivo studies that are needed to understand the relationship between breast density and cancer risk, thus paving the way for developing a simple, radiation-free risk assessment tool. A potential long term outcome, arising from these studies, is screening for high risk groups and safe monitoring of women undergoing preventive interventions, such as the use of tamoxifen or soy isoflavones. The ultimate goal of such screening and monitoring is a reduction in the incide

    Lay Abstract:
    In 1976, it was discovered that women with dense breasts were much more likely to develop breast cancer compared to other women. Although there are other factors that put women at risk for developing breast cancer, numerous studies have shown that breast density is one of the highest risk factors. Currently, the most effective way to measure breast density is with mammograms. Unfortunately, mammography has a number of drawbacks that have prevented wide-spread screening for breast density. First, tracking breast density under various conditions and times (e.g., phase of menstrual cycle) would lead to unnecessary exposure to ionizing radiation. Second, it is quite ironic that mammographic ability to find cancer markedly deteriorates as breast density increases. Consequently, mammography-based risk assessment has not been broadly accepted in the United States. We define the current gap in the knowledge base as ?the inability to develop a safe, efficient risk assessment tool for breast density measurements that also offers alternative detection for cancers missed by mammography in dense breasts?. We propose to bridge the gap in the knowledge base by using a new type of ultrasound exam, that analyzes ultrasound signals that travel through the breast, to assess the speed of sound as a measure of breast density. The hypothesis, based on our preliminary studies, is that the average sound speed of a woman?s breast is a measure of the breast?s overall mass density. We will test this hypothesis by (i) performing experiments on tissue-mimicking materials to determine the inherent accuracy of our approach and (ii) by examining additional patients to determine the potential of sound speed to measure breast density independent of mammography. A positive outcome would lead to the development of simple and quick breast density measurements. Larger human studies, utilizing this new approach, could then be conducted to understand the relationship between breast density and interventions that modulate breast cancer risk. A non-compressing, radiation-free risk assessment tool may then make it possible to safely screen high risk women and monitor those undergoing preventive interventions aimed at reducing breast density. The ultimate goal of such screening and monitoring is a reduction in the incidence of breast cancer.