Previous study has demonstrated that the mutations of some genes were predominantly associated with the initiation, progression and cancer therapy of CRC, such as APC, TP53, SMAD4, RAS, BRAF, PIK3CA and POLE. 18The inactive mutation of DNA mismatch repair (MMR) systems was reported to be dramatically correlated with MSI.19 This evidence concerns the gene SMAD4 and colorectal carcinoma.