The most recent clinical studies conducted by Cui et al. have underlined valuable results: PTX-3 low expression in gastric tissues is associated with macrophage polarization and stemness (represented by high capacity of invasiveness and EMT—epithelial–mesenchymal transition properties), through IL-4 and IL-10 secretion in the tumor microenvironment, while its increased expression inhibited migration of gastric cancer cell metastasis [109,110]. This evidence concerns the gene PTX3 and gastric cancer.