Cyclooxygenase is the main target enzyme for the nonsteroidal anti inflammatory drugs (NSAIDs) that have been shown to suppress carcinogenesis in both experimental models and epidemiological studies. COX-2 plays an important role in solid tumor growth, invasiveness and angiogenesis, through, in part, the synthesis of prostaglandins, such as prostaglandin E2 (PGE2). In this study, the prognostic significance of an increase in COX-2 expression in lung cancer samples was evaluated.

The expression of COX-2, by immunohistochemistry, was studied in paraffin-embedded tumor blocks obtained from 84 patients(male 67, female 17, with a mean age of 63, ranging from 34 to 84 years) who had undergone surgery at Wonkwang University Hospital, between 1997 and 2002. For the evaluation of the relationships between COX-2 expression, and the clinical stage, metastasis to lymph nodes and survival, those cases showing the respective antigen expression in >10% of the tumor cells were considered positive.

Of the 84 patients, 61 (73%) exhibited more than 10% COX-2 immunoreactivities in the tumor and normal cells, whereas the remaining 23 showed no increase in the expression of COX-2. There was no significant relationship between the increased expression of COX-2 and the disease stage(p=0.1002) or cell type(p=0.152). The median survival was longer for the patients with a negative, compared to positive, COX-2 expression(36 compared to 24 months, p<0.05). The two year-survival rate was also higher in the patients with a negative COX-2 expression (78%) than those with a positive expression (47%, Kaplan-Meier, Log Rank, p<0.05).

The median survival was longer in the patients with a negative, compared to positive, COX-2 expression was longer than those with positive COX-2, having undergone complete resection due to primary non-small cell lung cancer.