OBJECTIVE To study the relationship between the coxsackie and adenovirus receptor (CAR) and the development of human lung cancer. To optimize adenovirus vector-based gene therapy. METHODS The expression of CAR in 112 cases of lung cancer was examined using immunohistochemistry. At the same time, the relationship between CAR expression and clinicopathologic characteristics was analyzed. RESULTS There is a little expression of CAR in normal lung tissue. Compared with paraneoplastic epithelial tissue of the lung, the expression of CAR is generally up-regulated in tumor tissues showing a significant dif- ference (P<0.01). The positive rate of CAR expression in squamous cell carcinoma was 43.1%, and in adenocarcinoma 70.2%, with the difference between the two rates being statistically significant (P<0.01). Compared to the paraneoplastic tissues, the difference in CAR positive expression was 35.4% for squamous cell carcinoma and 38.3% for adenocarcinoma. But the difference in different stages of squamous cell carcinoma had no statistical significance (P>0.05). However, the expression of CAR was at a high level in the bronchioalveolar carcinomas as 80.4% were CAR positive. This research showed that there was a specially high expression of CAR in adenocarcino- mas. CONCLUSION CAR is expressed in human lungs at a low level and up-regulated in the tumor tissues, suggesting that there is a relationship between adenocarcinoma and CAR. This research provides a basis for plan- ning a regimen of gene therapy using an adenovirus vector. OBJECTIVE To study the relationship between the coxsackie and adenovirus receptor (CAR) and the development of human lung cancer. To optimize adenovirus vector-based gene therapy. METHODS The expression of CAR in 112 cases of lung cancer was examined using immunohistochemistry. At the same There was a little expression of CAR in normal lung tissue. Compared with paraneoplastic epithelial tissue of the lung, the expression of CAR is generally up-regulated in tumor tissues showing a significant The positive rate of CAR expression in squamous cell carcinoma was 43.1%, and in adenocarcinoma 70.2%, with the difference between the two significant differences (P <0.01). Compared to the paraneoplastic tissues , the difference in CAR positive expression was 35.4% for squamous cell carcinoma and 38.3% for adenocarcinoma. But the difference in different stage However, the expression of CAR was at a high level in the bronchioalveolar carcinomas as 80.4% were CAR positive. This research showed that there was a specially high expression of CAR in adenocarcino- mas. CONCLUSION CAR is expressed in human lungs at a low level and up-regulated in the tumor tissues, suggesting that there is a relationship between adenocarcinoma and CAR. This research provides a basis for plan- ning a regimen of gene therapy using an adenovirus vector.