Immunohistochemical detection of CD133 expression in colorectal cancer: a clinicopathological study.

CD133 has been reported to be a cancer-initiating cell marker in colorectal carcinoma. The objective of this study was to evaluate the frequency of CD133 expression in colorectal cancer, the distribution of CD133-positive cancer cells, and their relationship to clinicopathological features, including survival. An immunohistochemical examination of CD133 expression and a clinicopathological analysis were performed in the 189 consecutive colorectal cancer patients. CD133 expression was seen at the luminal surface of cancer glands mainly with cribriform features. Expression was detected in only 29 of the 189 tumors (15.3%). Of these, 21 tumors (11.1%) showed CD133 overexpression. All 21 tumors with CD133 overexpression were diagnosed as well- or moderately-differentiated adenocarcinoma. There was no difference in the distribution of CD133 expressing cells between the invasive area and surface area. Although there was no difference in recurrence-free survival between patients with CD133 overexpression and without, the patients with CD133 overexpression had significantly poorer overall survival (P = 0.03). CD133 overexpression is a risk factor for poorer overall survival in patients with well- and moderately-differentiated adenocarcinoma. Expression of this cancer-initiating cell marker may vary with the histological type of the cancer, and further investigation of the relationship between its expression and clinicopathological features may be necessary.