Leptin and leptin receptor expression in breast cancer.

PURPOSE: Leptin is a multifunctional hormone that's produced by adipose tissue and leptin is involved in the regulation of food intake and energy balance. The aims of this study were to determine the leptin and leptin receptor (Ob-R) expressions in human breast cancer and their corresponding influence on the prognosis of patients with breast cancer.
MATERIALS AND METHODS: We examined the correlations between the leptin and Ob-R expressions and the breast cancer-related pathobiologic markers by performing immunohistochemistry in 517 patients with breast cancer. We analyzed the leptin and Ob-R expressions with respect to overall survival and relapse-free survival (RFS).
RESULTS: Positive cytoplasmic immunoreactivity for leptin was noted in 39% of the patients and 79% of the patients showed positive cytoplasmic immunoreactivity for Ob-R. The expression of leptin in breast cancer was correlated with a high Ki-67 labeling index (p=0.019). Based on the univariate survival analysis, the clinicopathologic variables with prognostic value included the histologic grade, the T stage, the N stage, the HER2 status, the Bcl-2, p53 and Ki-67 expressions (p<0.05). The patients with leptin-positive breast cancers and a negative hormone receptor status had a significantly longer overall survival (p=0.021). Multivariate survival analysis showed that a positive expression of leptin was an independent prognostic marker for overall survival (hazard ratio, 0.20; 95% CI, 0.04~0.99; p=0.05).
CONCLUSION: A leptin expression in breast cancer is significantly associated with the Ki-67 labeling index, and this suggests there is an association of a leptin expression with the proliferation activity. In addition, a leptin expression is an indicator of better survival for breast cancer patients.