KEAP1 and thyroid cancer: Aberrant methylation at the promoter island of the KEAP1 gene has been widely reported as one of the most important mechanisms of KEAP1 silencing in solid tumors, such as glioma, breast, prostate, colorectal, thyroid cancers, clear renal cell carcinoma and lung cancer and was linked to tumor development, chemoresistance and mortality risk [14].