Clinical Significance of Cyclooxygenase Expression in Stage I Human Squamous Cell Carcinoma of the Lung

Abstract

Background. With early diagnosis and adequate resection, the 5-year survival rate for patients with stage 1 lung cancer is approximately 65%. Recent results of epidemiological studies have indicated that nonsterolidal anti-inflammatory drugs may reduce the risk of cancer; expressions of cycloxygenases (COX) are therefore anticipated to be associated with the prognosis of lung cancer patients. In this study, we evaluated the expressions of COX-1 and COX-2 in lung cancer cells and assessed their prognostic significance. Methods. From 1987 to 1997, we collected samples of stage I squamous cell carcinoma (SCC) of lung from 88 patients who had undergone complete surgical resection. Clinical data were recorded including the time and the location of tumor recurrence. Expressions of COX-1 and COX-2 in paraffin embedded tumor samples were determined by immunohistochemstry and scored with a semi-quantitative method. Results. Expressions of COX-1 and COX-2 were detected in 52(62.6%) and 59(71.1%) of 83 patients, respectively. Compared with patients with low COX-1 expression, patients with COX-1 expression had a significantly higher incidence of early tumor recurrence. Patients without COX-1 expression also had better survival rates than those with COX-1 expression. Using univariate analysis, expressions of COX-1, poor cell differentiation and smoking habits were the three important factors correlated with poor prognosis for patients with stage I SCC of lung. However, no significant difference was observed when COX-2 expression was used as a biological marker to evaluate the metastatic potential. Conclusions. COX-1 expression in stage I SCC of the lung predicted tumor aggressiveness. Early tumor recurrence is frequently occurred in patients with COX-1 expression.