Associations of adipokines & insulin resistance with sex steroids in patients with breast cancer

Background & objectives: Several studies have suggested an important, but conficting and controversial role for adipose tissue mass in breast cancer risk. Factors such as insulin-like growth factors, sex steroids, adipokines and obesity-related infammatory markers have been postulated as potential effectors of the mechanisms by which obesity and associated metabolic disorders infuence breast cancer risk. In this study we evaluated the associations between obesity indices, insulin resistance, circulating adipokines, sex steroids and breast cancer. Methods: Fasting adiponectin, leptin, insulin resistance (homeostasis model assessment, HOMA-IR), testosterone, estradiol, sex hormone binding globulin (SHBG), LH and FSH were determined in 144 newly-diagnosed histologically confrmed breast cancer patients and 77 controls. Univariate and multivariate regression analyses were used to fnd the associations of these variables with each other, indices of obesity and with breast cancer. Results: BMI, waist circumference, HOMA-IR and leptin were signifcantly (P<0.001) higher in patients than in controls. Adiponectin level was also signifcantly (P<0.05) higher in patients compared to controls. Adiponectin and leptin showed signifcant correlations with insulin and HOMA-IR but only adiponectin was signifcantly correlated with estradiol and SHBG. Logistic regression analyses showed that factors associated with breast cancer were BMI [OR (95% CI) =2.8 (1.4-5.5), P=0.004]; high levels of adiponectin [5.1 (2.2-11.5), P<0.001); hyperinsulinaemia [1.1 (1.0-1.1), P=0.01], leptin [3.1 (1.7-5.7), P<0.0001], estradiol [2.5 (1.3-4.7), P=0.005] and testosterone [1.3 (1.03-1.7), P=0.03]. Interpretation & conclusions: Our fndings confrm that adipokines, insulin resistance and sex steroids are associated with breast cancer. The paradoxical association of increased adiponectin with breast cancer is a novel fnding that deserves further investigation.