MGMT and laryngotracheoesophageal cleft: The eight genes were CDKN2, MGMT, DAPK1, RASSF1, GATA4, GATA5, PAX5α, and PAX5β. Three indexes, including low (0–1), medium (2–3), and high (≥ 4) methylation index, were used to assess the time to relapse for LC patients via the Kaplan–Meier analysis.