TOP2A and laryngeal carcinoma: Increased methylation levels of promoters of TOP2A (DNA topoisomerase II alpha), PLXDC2 (plexin domain containing 2), ETNK2 (ethanolamine kinase 2), GFI1 (growth factor independent 1 transcriptional repressor), and IL12B (interleukin 12B) were detected in radioresistant laryngeal cancer cells.