Significance of cyclin B1 expression as an independent prognostic indicator of patients with squamous cell carcinoma of the esophagus

Purpose: Cyclin B1 plays an important role as a mitotic cyclin in the G₂-M phase transition during the cell cycle. The aim of the present study was to elucidate the biological significance of cyclin B1 expression in squamous cell carcinoma (SCC) of the esophagus. Experimental design: We analyzed immunohistochemically the expression of cyclin B1 in the tumor specimens from 120 patients with SCC of the esophagus that had been treated with surgical treatment without any preoperative therapies. Results: The positivity rate of cyclin B1 expression was 56.7% (68 of 120). One-, 3-, and 5-year survival rates in esophageal SCCs with cyclin B1 expression were 82.8, 61.6, and 50.7%, respectively, and they were significantly lower than those in esophageal SCCs without cyclin B1 expression (97.8, 85.5, and 78.6%, respectively; P = 0.005). Cyclin B1 expression was found to be an independent prognostic indicator in esophageal SCCs in a multivariate analysis. When immunostaining for cyclin B1 was classified as a nuclear dominant pattern and cytoplasmic dominant pattern, 1-, 3-, and 5-year survival rates in esophageal SCCs with nuclear dominant expression of cyclin B1 were 66.7, 47.9, and 28.7 %, respectively, and they were significantly lower than those in esophageal SCCs with cytoplasmic dominant expression (92.5, 70.0, and 66.3%, respectively; P = 0.005). A multivariate analysis demonstrated that the nuclear dominant cyclin B1 expression was an independent prognosticator in patients with esophageal SCCs expressing cyclin B1. Conclusions: Our results demonstrate that cyclin B1 expression, especially nuclear dominant expression, can be significant as a prognostic indicator in esophageal SCCs.