Collectively, integrative analysis of the results in Figs. 4 and 5 indicates that the expression levels of CLU, SFTPD, CCL18, SPP1, APOE and BGN in other GEO datasets and TCGA database showed a consistent increase in metastatic CRC compared with primary CRC in GSE68468 and GSE41258. This evidence concerns the gene SPP1 and colorectal carcinoma.