INSULIN-LIKE GROWTH-FACTOR BINDING PROTEIN-3 IN BREAST CYST FLUID - RELATIONSHIPS WITH INSULIN-LIKE GROWTH-FACTOR-I AND GROWTH-FACTOR-II AND TRANSFORMING GROWTH-FACTOR-BETA-1 AND GROWTH-FACTOR-BETA-2

Women who have palpable breast cysts with intracystic Na/K > 3 may hav e a lower risk of developing breast cancer than those with intracystic Na/K < 3. In this study significantly higher concentrations of insuli n-like growth factor-binding protein-3 (IGFBP-3), insulin-like growth factors I and II (IGF-I, IGF-II) and transforming growth factor-beta 2 (TGF-beta(2)) were found in the Na/K > 3 sub-group. No difference was found in transforming growth factor-beta 1 (TGF-beta(1)) levels betwe en the two sub-groups of breast cysts. A positive correlation was obta ined for IGFBP-3 and TGF-beta(1) in the Na/K > 3 sub-group consistent with reports that TGF-beta(1) may regulate the production of IGFBP-3. Equimolar amounts of total IGFs and IGFBP-3 in breast cyst fluid imply that most, if not all, of these IGFs are protein-bound, The significa ntly higher concentrations of TGF-beta(2) in the Na/K > 3 sub-group ma y partly explain the lower risk of breast cancer in this group of wome n.