Predictive Value of DNA Mismatch Repair System in Colorectal Cancers

* Microsatellite instable (MSI) tumors represent almost the 15% of all sporadic colorectal cancers (CRCs). * Literature data show that this unique tumor population appears to be poorly responsive to conventional chemotherapy and conversely reveals excellent results to immunotherapy. * Our data, as demonstrated by propensity score-matched and win ratio analysis, show that there are no substantial differences between MSI and MSS tumors in early CRC stages treated with surgery alone. * On the contrary, stable tumors (MSS) did much better than MSI tumors in advanced CRC stages undergoing conventional adjuvant treatment. * Determination of status of DNA mismatch repair system is crucial in high-risk CRCs to optimize treatment.