In addition, Shimura et al. 33 demonstrated that serum CRP levels, before chemotherapy, might be a potential prognostic factor for metastatic GC, whereas Boire et al. 34 reported upregulation of C3 in leptomeningeal metastatic models, a common fatal condition, and further proved that this was essential for the spread of cancer cells in the leptomeningeal space. This evidence concerns the gene C3 and gastric cancer.