Abstract
Background : B7-h6, a member of the B7 family molecules, participates in the clearance of tumor cells by binding to NKp30 on NK cells. The expression of B7-H6 in esophageal squamous cell carcinoma (ESCC) and the clinical significance is unknown. The goal of this study was to determine the expression of B7-H6 in ESCC and further explore its clinical significance.
Patients and methods: We retrospectively collected clinical data from 145 patients diagnosed with ESCC between January 2007 and December 2008. These patients had all previously undergone surgical treatment for esophageal cancer, were clearly diagnosed, and had not received chemotherapy or radiotherapy. In addition, pathological tissue samples from the 145 patients were collected to detect the expression of B7-H6 by immunohistochemistry. The chi-square (χ2) test was used to analyse the relationships between B7-H6 and clinicopathological characteristics. The prognosis of the patients was analysed by Cox proportional hazards regression analysis and Kaplan-Meier analysis.
Results: 133/145 (91.72%) of the ESCC tissue samples exhibited B7-H6 expression. The expression level of B7-H6 was correlated with T stage (P=0.036) and lymphatic metastasis status ( P =0.044). According to the results of the ROC curve analysis, H-score =90 was selected as the cut-off value. The 145 patients were divided into two groups, the high B7-H6 expression (H-score＞90) group and the low B7-H6 expression (H-score≤90) group. Cox proportional hazards regression analysis indicated that tumour size ( P =0.021), B7-H6 expression ( P =0.025) and lymphatic metastasis status ( P =0.049) were independent prognostic factors for ESCC. Kaplan-Meier analysis with the log-rank test demonstrated that the patients with high B7-H6 expression ( P = 0.003), lymphatic metastasis ( P <0.001) or a tumour size ≥ 3.0 cm ( P = 0.001) had significantly worse survival than those with low B7-H6 expression, no lymphatic metastasis or a tumour size < 3.0 cm respectively.
Conclusion: Our findings suggest that B7-H6 is widely expressed in ESCC samples. And B7-H6 may represent a predictor of poor prognosis for ESCC.
Keywords: B7-H6, Esophageal squamous cell carcinoma, Immunohistochemistry, prognosis.
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