In gastric cancer (GC), leptin expression is associated with that of the proto-oncogene human epidermal growth factor receptor (HER)2, which in turn is associated with invasion, lymph node metastasis, tumor stage [61] and expression of VEGF [61], intercellular adhesion molecule (ICAM)-1 (CD54) [62], and matrix metalloproteinase (MMP)14, which plays crucial roles in tumor invasion [63]. This evidence concerns the gene ERBB2 and gastric cancer.