Immunohistochemistry for CDX2, hMLH1, and hMSH2 was applied to a study cohort of 503 CRC specimens (FIRE-3) and a matched case-control collection of 50 right-sided CRC specimens with synchronous distant metastases and 50 right-sided CRCs without distant metastases.
A total of 1252 tumors (index tumors) and all secondary malignancies were tested for MMR by immunohistochemistry (MSH2, MSH6, MLH1, PMS2) between 1992 and 2013.
The expression of hMSH2 correlated positively with the expression of p53, with the appearance of distant metastases, low differentiation and the appearance of hemangiosis carcinomatosa and lymphangiosis carcinomatosa, while it negatively correlated with the expression of the estrogen receptor.