Lack of M30 expression correlates with factors reflecting tumor progression in rectal cancer with preoperative chemoradiotherapy.

Preoperative chemoradiotherapy (CRT) is an effective tool for local control that functions by inducing cancer cell apoptosis and inhibiting cell growth. The aim of this study was to evaluate the expression of caspase-cleaved keratin 18 cytoskeletal protein, M30, which is known as an apoptotic marker in residual rectal cancer following preoperative CRT. A total of 72 patients with rectal cancer who had undergone preoperative CRT were enrolled in this study. Immunostaining with M30 cytodeath antibody was performed and the correlation between M30 staining and clinicopathological variables was analyzed. Furthermore, we examined the correlation of M30 staining with the expression of Bax, Bcl-2, Ki67 and PCNA using transcriptional and immunohistochemical analyses. The results showed that 34 (47%) patients were positive for M30 staining. Lack of M30 expression was significantly correlated with advanced T stage, postoperative stage and tumor recurrence (P<0.05). Patients with M30 staining had better recurrence-free survival (RFS) than those without it (P=0.0301). In the immunohistochemical analysis, residual cancer cells with M30 staining lacked Ki67 expression. No significant correlation was observed between M30 positivity and the gene expression of apoptotic and proliferative markers. In conclusion, findings of the present study suggested that the evaluation of M30 expression may be useful in the prediction of tumor recurrence in rectal cancer patients who have been treated with preoperative CRT.