The Stromal Overexpression of Decay Accelerating Factor (DAF/CD55) Correlates with Poor Clinical Outcome in Colorectal Cancer Patients

Background: Decay accelerating factor (DAF/CD55), regulates the complement system by accelerating decay of the C3 convertase, has been described in several malignancies, however, the clinicopathologic significance of CD55 and its receptor CD97 has not been fully investigated. We examined the expression patterns of both CD55 and CD97 and their association with clinicopathologic parameters in colorectal cancers (CRCs). Methods: Expression patterns of CD55 and CD97 in the stroma and tumor cells at tumor center and invasive front were examined in 130 CRCs, and their significance was statistically evaluated. Results: CD55-high stroma was correlated with tumor border (p = 0.006) and invasion depth (p = 0.013). CD55-high tumor cells at tumor center and invasive front were correlated with histologic grade, and CD55-high tumor cells at invasive front with tumor, node and metastasis (TNM) stage (p < 0.05). CD97-high stroma was correlated with lymph node metastasis (p = 0.016) and TNM stage (p = 0.030). CD97-high tumor cells at tumor center and invasive front were correlated with tumor size and CD97-high tumor cells at tumor center with tumor border (p < 0.05). Patients with CD55-high stroma showed poor overall and recurrence-free survival (p < 0.05) in univariate analysis, and were independently associated with short recurrence-free survival (p = 0.025) in multivariate analysis. Conclusions: Stromal CD55 overexpression would be an indicator of adverse clinical outcome and a useful prognostic factor.