MIB-1 index is unlikely to predict relapse-free survival in patients who underwent R0-esophagectomy for esophageal squamous cell carcinoma

MIB-1 is a cell proliferation marker and has previously been investigated as a diagnostic or prognostic indicator of malignancy. Previous studies have investigated MIB-1 index and clinicopathological factors in relation to prognosis of patients with esophageal cancer, with conflicting results. The aim of this study is to assess the prognostic significance of MIB-1 index in patients with thoracic esophageal squamous cell carcinoma. A total of 78 patients who underwent R0-esophagectomy for thoracic esophageal squamous cell carcinoma were enrolled in this study. Preoperatively, 29 patients underwent chemotherapy, six underwent chemoradiotherapy, and the remaining did not undergo any preoperative therapy. The MIB-1 labeling index was reported by counting 500 tumor cells in the hot spots of nuclear labeling. Correlations between MIB-1 index, clinicopathological factors, and relapse-free survival (RFS) were investigated. The mean MIB-1 index was 39.3 +/- 21.0 (range: 0-91.3). There was no significant correlation between clinicopathological factors and MIB-1 index in the study patients, irrespective of whether they underwent preoperative therapy. Univariate analysis revealed no significant association between MIB-1 index and RFS. However, depth of tumor invasion, lymph node metastasis and stage, all showed a significant correlation to RFS. Multivariate analysis of RFS revealed that stage was the only significant factor. Conversely, MIB-1 index was not significantly related to RFS (p = 0.41). In conclusion, MIB-1 index is unlikely to be a significant prognostic indicator for esophageal cancer.