Prognostic Significance of NBS1 and Snail Expression in Esophageal Squamous Cell Carcinoma

Background. Esophageal squamous cell carcinoma (ESCC) is a lethal malignancy, but only limited molecular markers can predict its prognosis. Recently, a DNA double-strand break repair protein Nijmegen breakage syndrome 1 (NBS1) was reported to induce Snail expression and predict poor prognosis in head and neck cancers. However, the clinicopathologic roles of NBS1 and Snail in ESCC remain unclear. Methods. From January 1995 to September 1999, tissue samples from 153 patients with ESCC who underwent esophagectomies at our institutions were collected and made into tissue core arrays for study. Expression of NBS1 and Snail was examined by immunohistochemical staining. The clinicopathologic data were analyzed, and some additional studies were performed to explore the relationship between NBS1 and Snail. Results. NBS1 overexpression was observed in 28.1% (43/153) of ESCC, whereas Snail overexpression was observed in 26.1% (40/153) of ESCC. Overexpression of NBS1 correlated inversely with nodal status (P = 0.009) and was associated with better overall survival (P = 0.002). On the other hand, overexpression of Snail correlated positively with lymphovascular invasion (P = 0.034) and was associated with worse overall survival (P = 0.036). Meanwhile, NBS1 overexpression correlated inversely with Snail overexpression marginally (P = 0.084). Using the Cox regression analysis, T status (P = 0.006), M status (P = 0.008), and NBS1 overexpression (P = 0.007) were the independent factors of overall survival. Conclusions. Our results showed that NBS1 overexpression was an independent factor of better survival and Snail overexpression predicted a worse survival in ESCC. Combination of NBS1 plus Snail expression status could be used as a predictor of prognosis in ESCC.