We used the mean serum Apelin value (2.84 ng/mL) as a cut-off value to subgroup all GC patients: those with equal or higher than 2.84 ng/mL were assigned into high serum Apelin group (n = 160) and those with lower than 2.84 ng/mL were assigned into low serum Apelin group (n = 110). Here, APLN is linked to gastric cancer.