Ki-67 expression and prognosis for smokers with resected stage i Non–Small cell lung cancer

Background The cigarette smoking status of patients before surgery is an important prognostic factor in evaluation of stage I non–small cell lung cancer, and the proliferative activity of lung tumors is also related to the patient’s prognosis. This study evaluates relationships between various clinicopathologic factors, including tumor proliferative activity and smoking status, and the patient’s prognosis in stage I non–small cell lung cancer. Methods One hundred eighty-seven stage I adenocarcinoma and squamous cell carcinoma cases were evaluated. The patients underwent complete resection between 1988 and 1993 at Chiba University Hospital. Expression levels of Ki-67 nuclear antigen, p53 protein, and retinoblastoma protein were determined immunohistochemically, and postoperative survival rates for patients in the categories of clinicopathologic factors were estimated. Results The mean Ki-67 labeling index (LI) for all cases was 19.3%. Labeling index values were significantly higher in squamous cell carcinoma than in adenocarcinoma (p< 0.0001). Postoperative survival of adenocarcinoma patients was significantly related to the LI values and to the patient’s smoking status (p = 0.0164 and 0.0268, respectively). The LI values were also related to smoking status and the extent of histologic differentiation (p = 0.0112 and p< 0.0001, respectively). For nonsmoking adenocarcinoma patients, higher LI values were associated with abnormalities in p53 expression (p = 0.0048). Retinoblastoma protein abnormalities were not related to LI values. Conclusions In smokers with stage I pulmonary adenocarcinoma, tumor proliferative activity and smoking status before surgery were important prognostic determinants. The LI values were related to several clinicopathologic factors.