MRC1 and colorectal carcinoma: Finally, universal MMR-IHC, which should be performed routinely on all CRCs, has been an important and effective mechanism for identifying individuals who may have Lynch syndrome.12 While broadening eligibility for MGPT in CRC would obviate the need for MMR-IHC testing for Lynch syndrome screening, performing MMR-IHC or microsatellite instability testing on CRCs would still need to be performed for therapeutic decision making, including immunotherapy eligibility.30