Frequency and pattern of expression of the stem cell marker CD133 have strong prognostic effect on the surgical outcome of colorectal cancer patients.

CD133 has been reported to be a cancer stem cell marker in colorectal cancer (CRC). The aim of this study was to examine the frequency and pattern of CD133 expression by immunohistochemical methods and evaluate their correlation with clinicopathological features, including patient survival (PS) and recurrence. Tissue specimens of 151 CRC patients who underwent surgical treatment for well-differentiated/moderately differentiated adenocarcinoma and stage I-IV tumors (TNM classification) were immunostained for analyzing CD133 expression. The frequency of CD133 expression was 91.4% (138/151), and the pattern of expression was divided into membranous and cytoplasmic expression. Of the 151 patients, 136 (90.1%) showed membranous expression, whereas 44 (29.1%) showed cytoplasmic expression. Both expression patterns were seen in 42 (27.8%) patients. The frequency of CD133 overexpression (>50% of stained cells) was 27.2% (41/151); univariate analysis showed CD133 overexpression to be significantly associated with PS, but not recurrence, and multivariate analysis indicated it to be an independent prognostic factor. Multivariate analysis showed membranous overexpression (>50% of stained tumor cells on the membrane), which significantly correlated with histology and chemoresistance of recurrent and stage IV tumors, to be an independent prognostic factor for PS and recurrence. However, multivariate analysis did not indicate cytoplasmic expression, which significantly correlated with histology, lymph node metastasis, TNM stage and lymphatic invasion, as an independent prognostic factor for PS and recurrence. Our results demonstrated that evaluation of the frequency and pattern of CD133 expression is useful for predicting prognosis, recurrence, and chemosensitivity in CRC patients.