Association between transillumination breast spectroscopy and quantitative mammographic features of the breast

Transillumination breast spectroscopy (TiBS) uses nonionizing optical radiation to gain information about tissue properties directly from the breast. TiBS measurements were obtained from 225 women with normal mammograms. Principal component analysis was used to reduce the spectral data set into four principal components and to generate four TiBS scores (t(1)-t(4) for each woman. These components and scores represent light scattering, water, lipid, and hemoglobin content. Percent density, dense area, and nondense area were measured using Cumulus. The association between TiBS scores and quantitative mammographic features was analyzed using linear regression stratified by menopausal status and adjusted for body mass index. Among premenopausal women, t(1) and t(3) were significantly associated with percent density (beta(t1) = -0.14, P = 0.04; beta(t3) = -2.43, P < 0.0001), whereas t(2) and t(3) were significantly associated with dense area (beta(t2) = -1.57, P < 0.0001; beta(t3) = -2.54, P < 0.0001). Among postmenopausal women, t(1), t3, and t(4) were significantly associated with percent density (beta t(1) = -0.30, P < 0.0001;) <beta(t3) = -2.51, P < 0.0001;) beta(t4) = 4.75, P < 0.0001) and dense area (beta(t1) = -0.19, P = 0.004; beta(t3) = -2.13, P = 0.002; beta(t4) = 5.02, P < 0.0001). Scores t(2) and t(4) were also significantly correlated with age among postmenopausal women (r(t2) = 0.41 and r(t4) = -0.36). Given the association with quantitative mammographic features and tissue changes related to age and menopause, TiBS scores may prove useful as intermediate markers in studies of breast cancer etiology and prevention.