These selected genes were separated into the risky type (STC1, CLDN9, NT5E, CXCR4), with HR>1 related to poorer prognosis, and the protective type (EFNA3, ZBTB7A, NUP50), with HR <1 related to better prognosis (Table 2), among which five genes (STC1, CLDN9, ZBTB7A, NT5E, CXCR4) were also considered as independent prognostic factors of GC. Here, CLDN9 is linked to gastric cancer.