MLH1 and colorectal carcinoma: For sporadic CRC, the pooled prevalence of MLH1 promoter methylation was 73.6% (95% CI: 67.3–79.0%) in MSI-H CRC, 67.3% (95% CI: 47.1–82.7%) in MSI CRC, and 17.5% (95% CI: 10.0–29.0%) in MSS CRC (P<0.001; Table 2).