GKN2 promoter methylation level of 41–60‐ and 61–80‐year‐old group was significantly higher than its adjacent cancer tissues (p < 0.001, p < 0.001) while 21–40‐ and 81–100‐year‐old group did not differ significantly in LUAD (Figure 2D). The gene discussed is GKN2; the disease is cancer.