AYA patients were more often had a normal preoperative CEA level (CEA >5μg/L, 7.9% vs. 16.8%, p = 0.001), poorly differentiation (85.1% vs. 63.3%, p < 0.001), had perineural invasion (3% vs. 0.9%, p = 0.009), and underwent adjuvant chemotherapy (59.9% vs. 44.5%, p < 0.001), and less often had tumor located in the upper third of stomach (12.9% vs. 31.6%, p < 0.001). The gene discussed is CEACAM5; the disease is neoplasm.