Objective      To detect the apurinic/apyrimidinic endonuclease (APE1) expression and its correlation with prognosis of non-small cell lung cancer.        Methods      The expression of APE1 was detected by immunohistochemistry in 103 cases of non-small cell lung cancer and 36 normal lung tissues. High expression group and low expression group were defined according to the staining intensity of APE1

and its association with clinicopathologic data and prognosis of non-small cell lung cancer was analyzed.        Results      Protein expression of APE1 was noticed in all non-small cell lung cancer and normal lung tissues. The APE1 expression of normal lung tissues mainly located in nucleus

while APE1 expression of non-small cell lung cancer in cytoplasm. APE1 expression was not related with age and gender

tumor size

lymphatic metastasis

nor pathological classification. There was a significant correlation between expression levels of APE1 and prognosis by Kaplan-Meier survival curve.       Conclusion      High expression of APE1 and shift of APE1 location was associated with non-small cell lung cancer. High expression of APE1 protein may indicate poor prognosis.