Abstract
BackgroundCyclooxygenase-2 (COX-2) is believed to be an important enzyme in the pathogenesis of colorectal cancer (CRC). Correlations between the expression of COX-2 with tumor growth and distant metastasis have become an issue; thus, attention has been paid to COX-2 as a prognostic factor. Various studies examined the relationship between COX-2 immunohistochemistry (IHC) overexpression with the clinical outcome in patients with colorectal cancer, but yielded conflicting results. The prognostic significance of COX-2 overexpression in colorectal cancer remains controversial.MethodsElectronic databases updated to October 2012 were searched to find relevant studies. A meta-analysis was conducted with eligible studies which quantitatively evaluated the relationship between COX-2 overexpression and survival of patients with colorectal cancer. Survival data were aggregated and quantitatively analyzed.ResultsWe performed a meta-analysis of 23 studies (n = 4567 patients) that evaluated the correlation between COX-2 overexpression detected by IHC and survival in patients with colorectal cancer. Combined hazard ratios suggested that COX-2 overexpression had an unfavorable impact on overall survival (OS) (HR [hazard ratio] = 1.193, 95% CI [confidence interval]: 1.02 ∼ 1.37), but not disease free survival (DFS) (HR = 1.25, 95% CI: 0.99 ∼ 1.50) in patients with colorectal cancer.ConclusionsCox-2 overexpression in colorectal cancer detected by IHC appears to have slightly worse overall survival. However, the prognostic value of COX-2 on survival in colorectal cancer still needs further large-scale prospective trials to be clarified.
Highlights
Colorectal cancer is a leading cause of mortality in many countries [1]
The major baseline characteristics of the 23 eligible publications were reported in Table 1 and Table 2
Meta-Analysis The results of the meta-analysis were shown in Table 3 and Overall, the combined hazard ratio (HR) for all 18 eligible studies (17 publications) evaluating COX-2 overexpression on overall survival (OS) was 1.19, suggesting that COX-2 overexpression detected by IHC was an indicator of poor prognosis for colorectal cancer
Summary
The main prognostic factors in colorectal cancer are clinicopathological characteristics of the disease, including tumor size, stage, and grade. These parameters do reflect biological features of the tumor, they do not fully predict individual clinical outcome. Researches have focused on the potential role of new biological factors involved in the carcinogenic process as prognostic markers to aid accurate prediction of clinical outcome of patients with colorectal cancer. Cyclooxygenase-2 (COX-2) is overexpressed in the tumor tissue compared to the normal colonic mucosa [10]. Various studies examined the relationship between COX-2 immunohistochemistry (IHC) overexpression with the clinical outcome in patients with colorectal cancer, but yielded conflicting results. The prognostic significance of COX-2 overexpression in colorectal cancer remains controversial
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