p185(HER‐2/neu) and p21(CIP1/WAF1) Expression in Primary Tumors and Lymph Node Metastases in Non‐small Cell Lung Cancer

p185(HER‐2/neu), a tyrosine kinase receptor, is one of the target molecules for cancer therapy, and its expression may reduce the sensitivity of tumor cells to anti‐cancer drugs. p21(CIP1/WAF1) is a cyclindependent kinase inhibitor, and its expression may also be involved in chemoresistance. Non‐small cell lung cancer (NSCLC) is a potentially systemic disease, and systemic therapies play an important role in its treatment. However, there have been no studies comparing the expression of these molecules between primary and metastatic tumors. We investigated the expression of p185(HER‐2/neu) and p21(CIP1/WAF1) in 57 paired samples of primary NSCLC tumors and corresponding lymph node metastases by immunohistochemistry. Expression of each of p185(HER‐2/neu) and p21(CIP1/WAF1) was highly correlated between primary tumors and lymph node metastases, and similar correlations were also obtained when adenocarcinoma and squamous cell carcinoma cases were analyzed individually. However we failed to detect any correlation between p185(HER‐2/neu) and p21(CIP1/WAF1) expression. Our results suggested that expression of both p185(HER‐2/neu) and p21(CIP1/WAF1) is concordant between primary and metastatic tumors.