Fourthly, some more important molecular pathological data including KRAS, BRAF, PIK3CA, HER-2, ER, PR, and PD-L1 status, microsatellite instability status, CpG island methylator phenotype, microRNA expression, and other influential prognostic factors, which had been identified to be associated with specific cancer patient survival (35–42), could not be analyzed separatedly due to unavailability of these data in the included studies. This evidence concerns the gene KRAS and cancer.