We also saw a significant association between reduced osteoprotegerin expression and the multiplicity and bilobar involvement of metastatic tumors and the occurrence of recurrent liver metastasis, which corroborates our previous findings that reduced osteoprotegerin expression is significantly associated with aggressive oncogenic behavior in primary colorectal carcinoma, including larger tumor size, higher histological grade, lymph node metastasis, colorectal liver metastasis, advanced stage, and vascular invasion [4]. This evidence concerns the gene TNFRSF11B and metastasis.