Researchers have demonstrated that HOXA9 promoter methylation is responsible for its aberrant expression in lung adenocarcinoma (LUAD) [31], non-small cell lung cancer (NSCLC) [24, 25], high-grade noninvasive bladder cancer [29], and HNSC [59, 60]. The gene discussed is HOXA9; the disease is non-small cell lung carcinoma.