IGFBP3 and breast fibrocystic disease: To assess the possible associations between the IGF system and TDLU involution, we evaluated serum levels of IGF-I, IGFBP-3 and the molar ratio of IGF-I:IGFBP-3 among women with benign breast disease in relation to three standardized, reproducible quantitative measures that are inversely related to TDLU involution [6]: numbers of TDLUs per unit of tissue area (TDLU count), the diameter of the TDLU (TDLU span), and acini counts per TDLU.