Cyclo‐oxygenase‐2 over‐expression in sporadic colorectal carcinoma without lymph node involvement

Summary Background : Cyclo‐oxygenase‐2 over‐expression has been reported in most advanced human colorectal cancers. Aims : To assess the prevalence of cyclo‐oxygenase‐2 over‐expression in non‐advanced colorectal cancers, to investigate the correlation between cyclo‐oxygenase‐2 status and tumour clinicopathological features and molecular phenotype, and to determine the impact of cyclo‐oxygenase‐2 status on long‐term clinical outcome. Methods : Sixty‐one patients who had undergone surgery for colorectal cancer without lymph node involvement were evaluated retrospectively. Cyclo‐oxygenase‐2 expression was determined by immunohistochemistry. The tumour replication error phenotype was assessed by amplification of the two microsatellites, BAT‐25 and BAT‐26. Results : Thirty‐six tumours were classified as cyclo‐oxygenase‐2 positive and 25 as cyclo‐oxygenase‐2 negative. No correlation was found between cyclo‐oxygenase‐2 over‐expression and clinicopathological features or molecular phenotype. Cyclo‐oxygenase‐2 over‐expression was an independent predictor of a poor prognosis. Indeed, the relative risk of tumour recurrence or death for patients with cyclo‐oxygenase‐2‐positive tumours was 2.13 times that of patients with cyclo‐oxygenase‐2‐negative tumours (P = 0.008; 95% confidence interval, 1.22–3.73). This difference remained significant when post‐operative deaths were censored in the multivariate analysis (P = 0.014). Conclusion : Cyclo‐oxygenase‐2 over‐expression is not associated with tumour phenotype, but is indicative of a poorer clinical outcome in patients with non‐advanced colorectal carcinoma.