We summarized the research progress of PSK for gastric cancer treatment in the past 20 years, and research showed that the actions of PSK on anti-gastric cancer include inhibiting the expression of immunosuppressive factors such as TGF-β; activating immune responses, such as promoting the maturation of dendritic cells and correcting Th1/Th2 imbalances; and enhancing the activity of anticancer drugs (Figure 2) [39]. This evidence concerns the gene TGFB1 and gastric cancer.