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6th International Workshop on Breast Densitometry and Breast ...

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6 th <str<strong>on</strong>g>Internati<strong>on</strong>al</str<strong>on</strong>g> <str<strong>on</strong>g>Workshop</str<strong>on</strong>g> <strong>on</strong> <strong>Breast</strong> <strong>Densitometry</strong><br />

<strong>and</strong> <strong>Breast</strong> Cancer Risk Assessment<br />

P30 GENETIC DETERMINANTS OF FIBROGLANDULAR BREAST TISSUE:<br />

IMPLICATIONS ON USING MAMMOGRAPHIC DENSITY MEASURES IN BREAST<br />

CANCER RISK ASSESSMENT<br />

D. K<strong>on</strong>tos 1* , B. Keller 1 , S. M. Domchek 2 , J. Chen 3 , E. H<strong>and</strong>orf 2 , M. J<strong>on</strong>es 2 , L. Boghossian 2 , K.<br />

Armstr<strong>on</strong>g 2 , E. C<strong>on</strong>ant 1<br />

University of Pennsylvania, Departments of Radiology 1 , Medicine 2 , <strong>and</strong> Epidemiology 3<br />

<strong>Breast</strong> density, typically measured as the percent area of mammographically dense tissue, is a str<strong>on</strong>g risk<br />

factor for breast cancer. Currently, the biological determinants of the associati<strong>on</strong> between breast density<br />

<strong>and</strong> the risk of breast cancer are not yet fully understood. We investigate potential genetic determinants of<br />

breast density, by examining the associati<strong>on</strong> between new measures of fibrogl<strong>and</strong>ular tissue volume,<br />

versus the st<strong>and</strong>ard percent area density measures, <strong>and</strong> a series of validated single nucleotide<br />

polymorphisms (SNPs) associated with established breast cancer susceptibility loci. Bilateral two-view<br />

full-field digital mammography (FFDM) images were retrospectively analyzed under HIPAA <strong>and</strong> IRBapproval<br />

from 433 women (59.6% Caucasian, 40.4% African American, Age 53±7yrs, Gail Risk Lifetime<br />

Risk 10.4±4.4) with a negative screening exam who had results available from a validated genetic assay<br />

for breast cancer risk assessment (deCODE <strong>Breast</strong>Cancer, deCODE genetics, Inc.).<br />

ABSTRACTS<br />

This genetic assay measures the allelic variati<strong>on</strong> for 12 validated SNPs previously associated with breast<br />

cancer risk. Fibrogl<strong>and</strong>ular breast tissue volume, both in terms of relative (%) <strong>and</strong> absolute amount (cm 3 ),<br />

was measured <strong>on</strong> a per-breast basis using validated FDA-cleared automated software (Quantra TM ,<br />

Hologic, Inc). Mammographic area percent density (PD%) was estimated with our previously validated<br />

computer algorithm based <strong>on</strong> automated intensity clustering <strong>and</strong> thresholding. The fibrogl<strong>and</strong>ular tissue<br />

measures were averaged between the left <strong>and</strong> right breasts for each woman to create corresp<strong>on</strong>ding<br />

measures <strong>on</strong> a per-woman basis. Associati<strong>on</strong>s between each SNP <strong>and</strong> the fibrogl<strong>and</strong>ular tissue measures<br />

were assessed with univariate linear regressi<strong>on</strong>. Model adjustments were c<strong>on</strong>sidered for age, ethnicity,<br />

<strong>and</strong> Gail lifetime risk. B<strong>on</strong>ferr<strong>on</strong>i correcti<strong>on</strong> was also applied to adjust for multiple comparis<strong>on</strong>s across<br />

the different models.<br />

Statistically significant associati<strong>on</strong>s (p

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