Low serum leptin level in colon cancer patients without significant weight loss

Aims and background: Leptin is a protein that affects the metabolic, neuroendocrine, reproductive and hematopoietic systems and is involved in the regulation of body weight. The possible role of leptin in cancer patients, whose aforementioned systems show disorders at various levels, has been investigated by only a few studies and the results are quite contradictory. Methods: In this study serum leptin levels were investigated in 36 patients with colon cancer having no weight loss or anorexia and in 36 healthy volunteers. Serum leptin levels were measured by radioimmunoassay. Results: Significantly positive correlations were found between serum leptin level and/or body mass index (BMI) in patient and control groups (r = 0.842, P < 0.001 and r = 0.785, P < 0.001; r = 0.880, P < 0.001 and r = 0.523, P = 0.001). Serum leptin levels of colon cancer patients were significantly lower than those of the control group (8.79 vs 15.95 ng/mL, P = 0.003). BMI and age of the colon cancer patients were not different from those of the control group. Serum leptin levels of early-stage patients (n = 15) did not differ from those of advanced-stage patients (n = 21) (7.74 vs 9.54 ng/mL, P = 0.542), nor was there any difference in the serum leptin levels of patients who did and patients who did not receive chemotherapy. There was no correlation in cancer patients between serum leptin levels and CEA or CA19-9 (r = 0.015, P = 0.929 and r = 0.097, P = 0.574). Conclusion: Low serum leptin levels found in colon cancer patients without weight loss suggest that another mechanism regulating the leptin levels might be responsible.