In summary, the most prognostic coexpression network modules reveal a series of pathways representing complex cross‐talks among epithelial, stromal and immune cells in GC (Fig. 5a), which are potentially driven by environmental factor (i.e., EBV infection), genetic alterations (i.e., NEB and PIK3CA mutations) and epigenetic alterations (i.e. hypo‐/hyper‐methylations). Here, PIK3CA is linked to gastric cancer.