The CCL1 gene was selected for further study by considering the following: Among the five top candidate genes, CCL1 gene expression has the largest gap between CRC primary sites and liver metastatic sites; previous studies have demonstrated that CCL1 progresses clinically and biologically in several solid tumours,14, 15, 16, 17 which might also support the mechanism of altered tumour activity in our study. Here, CCL1 is linked to neoplasm.