Background Sirtuin 1 (SIRT1) has been reported to have diverse roles in various biological processes through deacetylation of histone and nonhistone proteins.However,the correlations among SIRT1 protein expression,clinicopathological parameters,and survival of colorectal cancer patients remain unclear.Methods SIRT1 protein expression was measured by immunohistochemistry in a paraffin-embedded tissue microarray,including 120 paired colorectal cancer and normal mucosa tissues.The correlations among SIRT1 protein expression,clinicopathological features,and prognosis were analyzed.Results All samples (100％) were positive for SIRT1,with variable staining in the cytoplasm rather than in the nucleus.There was significant difference in SIRT1 overexpression between adenocarcinomas and normal mucosal tissue (P＜0.01,x2 test).SIRT1 overexpression was more frequently observed in advanced-stage tumors (P=0.046,0.002,x2test).SIRT1 overexpression was significantly correlated with poor overall survival (P=0.013,log-rank test) and diseasefree survival (P=0.012,log-rank test).Conclusions SIRT1 overexpression correlated with advanced stage and poor prognosis.SIRT1 may play an important role in the progression of colorectal cancer.