THBS4 methylation increases with increasing CIMP methylation. Tumours were stratified according to the Laird classification of CIMP, separated into CIMP-neg (0/5 markers positive for methylation), CIMP-low (1/5 or 2/5 markers positive for methylation) and CIMP-high (3, 4 or 5/5 markers methylation positive) categories of methylation. THBS4 methylation was found to positively correlate with CIMP. The greater the number of Laird markers that were positive for CIMP, the higher the level of THBS4 promoter methylation. The median PMRs were 0.69 for CIMP-negative tumours, 3.4 for CIMP-L tumours, and 5.8 for CIMP-H tumours (p = 0.033).