Objective   To explore the individual or combined effects of adiponectin, leptin, and soluble leptin receptor (sOB-R) on risks for premenopausal and postmenopausal breast cancer, and to provide evidence for revealing the molecular mechanism between obesity and breast cancer.

  Methods  469 newly-diagnosed breast cancer cases were sequentially recruited for the study and 469 age-frequency-matched healthy women were enrolled as the controls over the same period of time. The participant baseline information was collected with questionnaires, and plasmic levels of adiponectin, leptin and sOB-R were checked with ELISA. Multivariate unconditional logistic regression was conducted and the analyses were further stratified according to waist-to-hip ratio (WHR) and body mass index (BMI) to explore the effect of the indicators on the risks for premenopausal and postmenopausal breast cancer.

  Results   A total of 480 premenopausal and 458 postmenopausal women were included in the study. Among the premenopausal subjects, 249 were breast cancer patients and 231 were controls. The median BMI was 22.9 kg/m² and 23.2 kg /m², respectively, and the median WHR was 0.80 and 0.83, respectively. Among the postmenopausal subjects, 220 were breast cancer patients and 238 were controls. The median BMI was 23.4 kg/m² and 23.7 kg/m², respectively, and the median WHR was 0.82 and 0.86, respectively. Multivariate logistic regression analysis showed that before and after model adjustment, the increase in sOB-R and adiponectin levels was correlated to reduced risks of premenopausal and postmenopausal breast cancer (P<0.05), while the increase in the leptin/sOB-R ratio (also known as free leptin index, FLI) and leptin/adiponectin (L/A) ratio was only correlated to increased risks of postmenopausal breast cancer. After further stratification by WHR and BMI, the association between adiponectin, FLI and postmenopausal breast cancer remained statistically significant in all subgroups. Among subjects with normal-BMI central obesity (18.5 kg/m²≤BMI<24 kg/m² & WHR≥0.85) , higher L/A ratio was associated with an increased risk of postmenopausal breast cancer. No clear association between leptin and premenopausal and risks for postmenopausal breast cancer was found in the study.

  Conclusion   Postmenopausal women with decreased levels of sOB-R and adiponectin, and increased FLI and L/A, and premenopausal women with decreased levels of sOB-R and adiponectin were found to be at high risks for breast cancer.