KRAS and neoplasm: In summary, serum LDH levels showed no statistical difference when stratified by demography characteristics (age and gender), primary tumor characteristics (tumor location, pathology differentiation, and T and N stage), metastatic site characteristics (presence of extrahepatic disease, number of CRLM, and perioperative chemotherapy), and KRAS and BRAF mutations (data not shown in Table 2 because gene test was not carried out in a minority of patients).