Low expression level of SMAD9 was correlated with better OS in all gastric cancer patients (HR = 1.67 (1.33–2.08), P = 5.4e-06, Figure 8(a)), gastrointestinal cancer patients (HR = 1.79 (1.16–2.77), P = 0.0081, Figure 8(b)), diffuse gastric cancer patients (HR = 1.79 (1.27–2.53), P = 0.00074, Figure 8(c)), and mixed gastric cancer patients (HR = 7.86 (1.01–60.93), P = 0.02, Figure 8(d)). Here, SMAD9 is linked to gastric cancer.