RELATIONS BETWEEN SEX-HORMONES, SEX-HORMONE BINDING GLOBULIN, INSULIN-LIKE GROWTH FACTOR-L AND INSULIN-LIKE GROWTH-FACTOR BINDING PROTEIN-1IN POSTMENOPAUSAL BREAST-CANCER PATIENTS

OBJECTIVE Oestrogens, androgens and anti-endocrine drugs such as tamox ifen and aminoglutethimide influence plasma insulin-like growth factor -I (IGF-I). IGF-I, in turn, has been found to stimulate the peripheral aromatase in vitro. The aim of this study was to examine relations be tween sex hormones, IGF-I and insulinlike growth factor binding protei n-1 (IGFBP-1) in post-menopausal women with breast cancer. DESIGN To m easure plasma sex steroids, sex hormone binding globulin (SHBG), IGF-I , IGFBP-1, insulin and urinary oestrogen metabolites in post-menopausa l women with breast cancer not receiving any endocrine therapy. PATIEN TS Thirty-two patients had fasting blood samples obtained between 0800 and 1000h. A sub-group of 10 patients had 24-hour urine oestrogen met abolites determined. MEASUREMENTS Plasma steroids and proteins were me asured by radioimmunoassays. Urinary oestrogens were measured by GC-MS . RESULTS SHBG correlated negatively with plasma androstenedione (P < 0.001), insulin (P < 0.001), IGF-I,height and plasma oestrone sulphate (P < 0.025 for all), but positively with plasma IGFBP-1 (P < 0.025). IGFBP-1 correlated negatively with IGF-I (P < 0.0001) and the testoste rone/SHBG ratio (P < 0.05). Neither IGF-I nor IGFBP-1 correlated with any of the plasma or urinary sex hormones or with the oestrone/androst enedione and oestradiol/testosterone ratios. Multivariate analysis rev ealed plasma SHBG to correlate positively with IGFBP-1 (P = 0.029) and negatively with insulin (P = 0.031). Plasma IGFBP-1 correlated negati vely with IGF-I (P < 0.0001) but not with insulin. CONCLUSION Our resu lts do not suggest any influence of plasma sex steroids in physiologic al concentrations on IGF-I or IGFBP-1 in post-menopausal breast cancer patients, nor do they indicate IGF-I at physiological concentrations influences the ratios between plasma oestrogens and their androgen pre cursors.