Cancer stem cell marker CD133+ tumour cells and clinical outcome in rectal cancer

Aims: The CD133 antigen has been identified as a putative stem cell marker in colorectal cancer tissues. According to the cancer stem cell hypothesis, CD133+ cells determine long-term tumour growth and are therefore suspected of influencing clinical outcome. The aim was to investigate the prognostic value of CD133 expression in rectal cancer patients after preoperative radiation and curative resection. Methods and results: The expression of the CD133 stem cell antigen in a series of 73 patients with rectal cancer of various ypTNM stages was analysed by immunohistochemistry on formalin-fixed paraffin-embedded sections. The prognostic value of CD133 expression and other clinicopathological factors was evaluated. On multivariate survival analysis, the proportion of CD133+ cells was a significant (P < 0.05) prognostic factor for adverse disease-free survival and overall survival independent of ypTNM stage, tumour differentiation or lymphovascular invasion. Conclusions: CD133 stem cell antigen expression correlates with patient survival in rectal cancer, lending support to the current cancer stem cell hypothesis.