MLH1 Hypermethylation Analysis, Tumor

Casandra

Casandra Test Code MC51611Version 1 (DRAFT)

Performing Lab

Lab Mayo Clinic LabLab Test ID ML1HMCPT Codes 81288, 88381

MLH1 Hypermethylation Analysis, Tumor

Clinical Use

Use

This test is used as an adjunct to tumor microsatellite instability and mismatch repair protein immunohistochemistry testing when colon or endometrial tumors demonstrate microsatellite instability (MSI-H) and loss of MLH1 protein expression. It helps in distinguishing a somatic versus germline event prior to performing expensive germline testing, and it is also an adjunct to negative MLH1 germline testing in cases where colon or endometrial tumors demonstrate MSI-H and loss of MLH1 protein expression.

Special Instructions

Pathology report and mismatch repair immunohistochemistry results must accompany the specimen for testing to be performed. This test should not be used as a first-tier screening measure for hereditary nonpolyposis colon cancer. Testing will only be performed on colon or endometrial tumors demonstrating loss of MLH1 protein expression by immunohistochemistry. Extracted DNA from tissues is not acceptable.

Limitations

Testing tumors other than colon or endometrial for MLH1 hypermethylation has not been fully evaluated, and these specimens are not accepted for testing. Colon cancer is relatively common, and a sporadic colon cancer may occur in a family with hereditary nonpolyposis colorectal cancer (HNPCC). Evaluation of other family members should still be considered in cases with MLH1 promoter hypermethylation if there is high clinical suspicion of HNPCC.

Test Details

New York Approved