Results of the KM plotter analysis showed that SMAD3 mRNA expression level affected the OS of all GC patients (1.86 (1.56–2.22), P = 1.6e-12, Figure 3(a)) and OS of gastrointestinal cancer patients (2.25 (1.62–3.13), P = 8.1e-07, Figure 3(b)). Here, SMAD3 is linked to gastric cancer.