World journal of clinical cases
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Colorectal cancer (CRC) is common in elderly patients. Mismatch repair (MMR) protein deletion is one of the causes of CRC. The RAS (KRAS/NRAS), BRAF, and PIK3CA genes are important gene targets in CRC treatment and are closely related to the prognosis and survival of patients. However, little is known regarding the relationship between the expression of MMR, RAS, BRAF, PIK3CA and the clinicopathological features in CRC patients. ⋯ In elderly CRC patients, the tumor is mainly located in the right colon, and the deletion rate of MMR protein is higher when the tumor diameter is greater than or equal to 5 cm; the deletion rate of MLH1 and PMS2 is more common; the mutation rate of KRAS gene is higher than that of the NRAS, BRAF and PIK3CA genes, the BRAF gene mutation has different degrees of correlation with clinicopathological characteristics; when the MMR protein is deleted, the BRAF and PIK3CA gene mutations are often present, and the KRAS gene mutation rate is low.