Leptin and TNF-α levels were also significantly higher in lymph node metastasis (LNM) positive cases than in LNM negative cases, with a pooled SMD of 0.80 (95% CI, 0.45, 1.14; P < 0.00001) and 0.63 (95% CI, 0.30, 0.96; P = 0.0002) respectively. Here, LEP is linked to metastatic malignant neoplasm in the lymph nodes.