Optical reflectance spectroscopy for prospective studies on breast cancer risk in adolescent girls.

A15

Prospective studies on diet and lifestyle effects on future breast cancer risk in young girls typically rely on establishing correlations between risk factors, and serum sex or growth hormones. Quantitative physical information on developing breast tissue is limited to breast density derived from DEXA at a cost of ionizing radiation exposure and the associated dose penalty. Near-infrared Optical Reflectance Spectroscopy (ORS) uses light to access structural and metabolic bulk tissue properties, providing quantitative physical and physiological information. Here we want to evaluate the ability of ORS to detect physiological and chromophore changes between different Tanner stages of breast development. Measurements were obtained from 7 adolescent girls ages 10 - 14 years. Spectrally resolved reflected light from 2 radial distances, 1.5 and 3.0cm, providing different sample depth, is detected. Principle Component Analysis (PCA) was used to reduce the spectral data and generate individual scores, representing physiologic and morphologic tissue information. Four principle components were identified accounting for 99.92% of the spectral variance. Radial distances and hence tissue volume interrogation, had an impact on ORS parameters t1, t2 and t4 (all at p<0.05, 2-tail independent t-test). Pearson correlation analysis indicated a positive correlation between t3 (r=-0.462, p<0.001) and increasing breast Tanner stages; t4 (r=0.240, p<0.011) showed a reverse relationship. r values were strengthened when adjusted for menarche status and radial distances. ORS may provide an alternative tool to DEXA to identify morphologic and physiologic changes to the breast tissue resulting from an intervention during the adolescent years, and will enable a much-improved sampling rate throughout the intervention.