Our key findings include following: 1) The mean level of SUVmax is significantly higher in the group with HER2 overexpression; 2) The levels of SUVmax are significantly associated with tumor size, differentiation, and status of Lauren histologic type; 3) HER2 overexpression, tumor size, and differentiation are an independent significant indicator of the level of SUVmax in AGC. The gene discussed is ERBB2; the disease is neoplasm.