Positive Relationship between CD133 Expression and Clinicopathologic Factors in Colorectal Cancer

The expression of the CD133 cancer stem cell marker correlates with metastasis and prognosis for many cancers, but no correlation has been established in colorectal cancer. We used immunohistochemical analysis to examine the relationship between CD133 expression and clinical malignancy factors such as lymph node metastasis and hepatic metastasis in colorectal cancer. The subjects of this study were 104 patients with colorectal cancer who were examined in our hospital and treated by surgical excision of the tumor between 2004 and 2007. Representative tissue sections were immunohistochemically stained using an anti-CD133 antibody. Patients showing staining of 50% or more of the tumor gland duct were classified into the CD133-positive group, which consisted of 36 patients. Those staining less than 50% of the tumor gland duct were classified into the CD133-negative group, which consisted of 68 patients. Patients with lymph node metastasis accounted for 63.9% of the positive group (23/36 patients) and 33.8% of the negative group (23/68 patients), and the difference was significant (P = 0.00331). Patients with hepatic metastasis accounted for 27.8% of the positive group (10/36 patients) and 10.3% of the negative group (7/68 patients), and the difference was significant (P = 0.0218). Classification of these patients according to cancer stage determined on the basis of the International Union Against Cancer (UICC) stage showed that five patients were in stage I, one patient in stage II, 20 patients in stage III, and 10 patients in stage IV in the positive group; and 20 patients were in stage I, 22 patients in stage II, 18 patients in stage III, and eight patients in stage IV in the negative group. There was a significant difference in the numbers of patients in each group (P = 0.000127). Differences in the number of patients with lymphovascular invasion and those with venous invasion were also significant between the groups (P = 0.0248 and P = 0.0292, respectively). No significant differences were observed for any other factors. These findings indicate that the CD133-positive group has a higher risk of metastasis.