IL6ST and neoplasm: To understand the clinical significance of DNA methylation of IL6, IL6R, and IL6ST genes, the OS and PFI analyses were performed stratifying the TCGA tumor samples according to the methylation levels of the highly representative cg13104385 and cg05265849 probesets of IL6 (negatively correlated in more than five tumor types) and cg09257526, cg04437762, and cg05756780 relative to IL6R (negatively correlated in more than 10 tumor types) (Table 2).