Elevated serum leptin levels: a risk factor for non-small-cell lung cancer?

OBJECTIVE: Leptin is intimately intertwined in the molecular pathophysiology of several cancer types; with regard to lung cancer, however, limited research has been conducted, with overall conflicting results. METHODS: The present case-control study comprises 66 non-small-cell lung cancer (NSCLC) cases and 132 healthy controls matched for gender and age. Lifestyle, sociodemographic and medical history information has been obtained in addition to body mass index (BMI) measurements and weight change during the last 2 months. Serum leptin and adiponectin levels were determined following a standard protocol. RESULTS: In multiple logistic regression analyses, elevated serum leptin emerged as a risk factor for NSCLC independent of central obesity, more pronounced after controlling for BMI and recent weight loss (odds ratio = 4.58, 95% confidence interval: 1.94-10.82). Additionally, smoking and animal foods consumption were strongly associated with the disease, whereas plant foods consumption showed a protective association. CONCLUSIONS: The observed higher serum leptin levels in NSCLC cases might be attributed to direct or indirect effects mediated by cancer- or cachexia-related cytokines. In line with the growth-promoting properties of leptin in the lung tissue documented elsewhere, increased serum leptin concentration may represent a tumor-promoting event during non-small-cell lung carcinogenesis.