SLC5A5 and cancer: Besides, similar degree of methylation was reported in PTC tumoral tissues (benign = 2.19 ± 0.50 AU, malignant = 1.92 ± 0.59 AU) and non-tumoral tissues (benign = 2.23 ± 0.58 AU, malignant = 2.20 ± 0.82 AU) and suggested that NIS promoter methylation is a common occurrence in benign and malignant tumors as well as in the surrounding tissues.