Use

MLH1 promoter methylation testing is used primarily to identify sporadic microsatellite unstable tumors, such as colorectal and endometrial cancers. MLH1 methylation is common in these sporadic tumors and is infrequently seen in Lynch syndrome (hereditary non-polyposis colorectal cancer, or HNPCC). The presence of MLH1 methylation in a tumor is suggestive of a sporadic cancer rather than Lynch syndrome, though rare cases of Lynch syndrome-associated MLH1 methylation have been reported. It aids in distinguishing these types in conjunction with other clinical evaluations.