Mammographic density does not differ between unaffected BRCA1/2 mutation carriers and women at low-to-average risk of breast cancer

Abstract #5002 Background: Mammographic density (MD) is one of the strongest risk factors for sporadic breast cancer. Since MD is a non-invasive, reproducible and quantitative measure, it has been proposed as a compelling intermediate marker in studies aimed at understanding breast cancer etiology and prevention. The mechanism by which MD influences breast cancer risk is unknown. However, epidemiologic evidence suggests that dense breast tissue may be, in part, genetically regulated. Increased MD has been positively associated with family history of breast cancer. Family studies of sisters, including twins, provide further support for a genetic influence on MD. The relationship between MD and BRCA1/2 mutation status is equivocal. Methods: We examined whether MD differed between unaffected BRCA1/2 mutation carriers ages 22-55 enrolled in the Clinical Genetics Branch's Breast Imaging Study (n=143) and women at low-to-average risk of breast cancer ages 25-79 enrolled in the same study (n=29) or the National Naval Medical Center's Susceptibility to Breast Cancer Study (n=90). Low-to-average risk women were defined as being BRCA mutation-negative members of mutation-positive families; or women with no personal history of breast cancer, a Pedigree Assessment Tool score