SMAD4 expression was significantly correlated with better OS for all gastric cancer patients (HR = 0.64 (0.53–0.77) P = 1.5e-06, Figure 4(a)), OS of gastrointestinal cancer patients (HR = 0.52 (0.38–0.72) P = 5.9e-05, Figure 4(b)) and OS of diffuse gastric cancer patients (HR = 0.57 (0.41–0.8), P = 0.0011, Figure 4(c)). Here, SMAD4 is linked to gastric cancer.