Association of serum soluble leptin receptor and leptin levels with breast cancer

Background: Leptin plays a key role in the regulation of energy expenditure and is known to circulate in both free and bound forms. Soluble leptin receptor (sOB-R) is a unique circulating form of leptin receptor that can bind to leptin. Leptin and leptin receptor have been implicated in processes leading to breast cancer initiation and progression. Our study was aimed to investigate the relationship between serum levels of sOB-R and leptin with breast cancer. Materials and Methods: Serum leptin and sOB-R levels were measured by enzyme-linked immunosorbent assay in 100 women with breast cancer cases compared with 100 age and body mass index (BMI)- matched controls without cancer. Lipid profi les were measured by enzymatic method. Results: Th e median serum levels of sOB-R in controls were signifi cantly higher than that in breast cancer cases (odds ratio [OR], 1.98; 95% confi dence interval [CI] = 0.77-188.2) versus (OR, 0.140; 95% CI = 0.09-98.1). Conversely, the median serum level of leptin in breast cancer cases was signifi cantly higher than that in controls (OR, 67.90; 95% CI = 2.77-129.9) vs. (OR, 28.30; 95% CI = 0.60-113.1). Breast cancer was signifi cantly associated with higher serum level of leptin (OR = 1.027, 95% CI = 1.017-1.038). Conversely, breast cancer was correlated with lower serum level of sOB-R (OR = 0.983, 95% CI = 0.969-0.997). Moreover, free leptin index (FLI) (leptin/sOB-R ratio) was associated with breast cancer (OR = 1.028, 95% CI = 1.015-1.042). Th e serum sOB-R level was negatively associated with leptin, BMI, and high density lipoprotein (r = −0.238, −0.186, and −0.168, respectively). Conclusion: Our results suggested that FLI and serum leptin level rather than serum level of sOB-R was associated with the breast cancer.