In a previous cross sectional study in a group of women without breast cancer and with varying degrees of parenchymal density patterns, a strong association was demonstrated between Transillumination Breast Spectroscopy (TIBS) and x-ray derived mammographic density. From this, we expect that TIBS should also provide a comparable odds ratio (4-6) as mammographic density for breast cancer risk shown in other independent epidemiological studies. It is possible that TIBS may provide complementary information and a higher odds ratio if compared to the incidence of breast cancer. In contrast to mammography derived parenchymal density pattern, no historical TIBS data is available for a retrospective analysis and hence a cross sectional study within a group of screened women is proposed. We hypothesize that TIBS provides physical information about the breast tissue which can be used to construct a breast cancer risk predictor with an odd ratio \> 6.