||Vachon CM, Scott CG, Fasching PA, Hall P, Tamimi RM, Li J, Stone J, Apicella C, Odefrey F, Gierach GL, Jud SM, Heusinger K, Beckmann MW, Pollan M, Fernández-Navarro P, Gonzalez-Neira A, Benitez J, van Gils CH, Lokate M, Onland-Moret NC, Peeters PH, Brown J, Leyland J, Varghese JS, Easton DF, Thompson DJ, Luben RN, Warren RM, Wareham NJ, Loos RJ, Khaw KT, Ursin G, Lee E, Gayther SA, Ramus SJ, Eeles RA, Leach MO, Kwan-Lim G, Couch FJ, Giles GG, Baglietto L, Krishnan K, Southey MC, Le Marchand L, Kolonel LN, Woolcott C, Maskarinec G, Haiman CA, Walker K, Johnson N, McCormack VA, Biong M, Alnaes GI, Gram IT, Kristensen VN, Børresen-Dale AL, Lindström S, Hankinson SE, Hunter DJ, Andrulis IL, Knight JA, Boyd NF, Figuero JD, Lissowska J, Wesolowska E, Peplonska B, Bukowska A, Reszka E, Liu J, Eriksson L, Czene K, Audley T, Wu AH, Pankratz VS, Hopper JL, dos-Santos-Silva I
||BACKGROUND: Mammographic density adjusted for age and body mass index (BMI) is a heritable marker of breast cancer susceptibility. Little is known about the biologic mechanisms underlying the association between mammographic density and breast cancer risk. We examined whether common low-penetrance breast cancer susceptibility variants contribute to interindividual differences in mammographic density measures. METHODS: We established an international consortium (DENSNP) of 19 studies from 10 countries, comprising 16,895 Caucasian women, to conduct a pooled cross-sectional analysis of common breast cancer susceptibility variants in 14 independent loci and mammographic density measures. Dense and nondense areas, and percent density, were measured using interactive-thresholding techniques. Mixed linear models were used to assess the association between genetic variants and the square roots of mammographic density measures adjusted for study, age, case status, BMI, and menopausal status. RESULTS: Consistent with their breast cancer associations, the C-allele of rs3817198 in LSP1 was positively associated with both adjusted dense area (P = 0.00005) and adjusted percent density (P = 0.001), whereas the A-allele of rs10483813 in RAD51L1 was inversely associated with adjusted percent density (P = 0.003), but not with adjusted dense area (P = 0.07). CONCLUSION: We identified two common breast cancer susceptibility variants associated with mammographic measures of radiodense tissue in the breast gland. IMPACT: We examined the association of 14 established breast cancer susceptibility loci with mammographic density phenotypes within a large genetic consortium and identified two breast cancer susceptibility variants, LSP1-rs3817198 and RAD51L1-rs10483813, associated with mammographic measures and in the same direction as the breast cancer association.