Plasma Leptin Level, the Adipocyte-Specific Product of the Obese Gene, Is Associated with Tumor Progression and Is a Marker of the Nutritional Status of Patients with Gastric Cancer

Leptin, a product of the obese gene, is synthesized and released into the circulation in response to increased energy storage in adipose tissue. Leptin plays an important role in the regulation of body weight and energy balance. However, leptin levels in patients with malignant tumor have not been fully examined. The purpose of the present study is to clarify the clinical implications of leptin levels in the circulation in patients with gastric cancer. The subjects were 103 patients with gastric cancer at various stages. Levels of leptin in the plasma were determined with a commercially available human leptin-selective quantitative enzyme immunoassay kit. There were clear decreasing trends in leptin levels along with tumor progression in both males and females, and statistically significant differences were observed in males between stages II and IV, and in females between stages I and IV. Plasma leptin levels of females were consistently higher than those of males when we compared them with patients in the same stages. Moreover, statistically significant decreases in leptin levels were observed postoperatively. However, there were no statistically significant relationships between leptin levels and clinicopathological findings. There was a positive correlation between levels of plasma leptin and values of the body mass index. These findings may indicate that plasma leptin levels do not involve factors relevant to specific tumor growth but involve some tumor-related nutritional status due to tumor progression. We conclude that leptin levels are reflected during tumor-bearing status, and these are also useful markers for both indicating tumor progression and discovering the nutritional status of patients with gastric cancer.