Objective      To determine the expression and clinical significance of breast cancer anti-estrogen resistance 1 (BCAR1) in human non-small cell lung cancer (NSCLC).       Methods      A total of 70 tissue samples of NSCLC and their adjacent normal tissues collected in our department during Feb 2006 to Feb 2007 were tested for BCAR1 protein ex

pression by tissue microarray (TMA) and immunohistochemistry (IHC)

Another 28 samples of benign pulmonary tumors (12 hamartoma

8 inflammatory pseudotumor

and 8 fibroid tumor) were used as control.       Results      BCAR1 protein was strongly expressed in NSCLC （98.6%

69/70）

while weakly expressed in 4.2% of adjacent normal tissues (3/70). However negative expression was found in benign pulmonary tumor. There was obvious difference in BCAR1 protein positive expression among aforesaid 3 groups (Chi square=143.93，

P

=0.000). BCAR1 protein positive expression had no correlation with age

gender

lymph node metastasis

TNM stage and pathological type of tumor（

P

>0.05）

and was negatively correlated with the degree of neoplastic differentiation（Chi square=13.639，

P

=0.001）. Surial analyses (Kaplan-Meier) indicated that BCAR1 low expression were in favor of survival in comparison with BCAR1 high expression（

P

=0.014）.       Conclusion      BCAR1 protein expression is significantly higher in NSCLC than adjacent normal tissues and benign pulmonary tumor

and has a negative correlation with the degree of neoplastic differentiation and prognosis. Therefore

BCAR1 protein might be used as a new marker of NSCLC for diagnosis and prognosis.