A new proliferation marker, minichromosome maintenance protein 2, is associated with tumor aggressiveness in esophageal squamous cell carcinoma

Abstract

Background: Our aim was to determine whether minichromosome maintenance protein (MCM) 2 expression is useful in predicting tumor proliferation rates and outcome after therapy in patients undergoing surgery for esophageal squamous cell carcinoma (SCC). In addition, we evaluated whether the expression of this proliferation marker was correlated with that of another marker, Ki-67, in esophageal SCC.

Methods: We examined immunohistochemical expression of MCM2 and Ki-67 in surgically resected tissues from 93 patients with esophageal SCC.

Results: The mean nuclear labeling index of MCM2 was markedly higher in SCC than in normal epithelia (P < 0.0001). A comparison of MCM2 labeling index and clinicopathological characteristics in 93 patients with esophageal cancer revealed significant associations between MCM2 labeling index and tumor status (P < 0.05), lymph node status (P < 0.01), metastatic status (P < 0.01), pathologic stage (P < 0.01), histologic grade (P < 0.05), and poor prognosis (P < 0.05). A comparison of Ki-67 labeling index and clinicopathological characteristics revealed significant associations between Ki-67 labeling index and lymph node status (P < 0.01), metastatic status (P < 0.05), pathologic stage (P < 0.05), histologic grade (P < 0.05), and poor prognosis (P < 0.05). The relationship between MCM2 and Ki-67 labeling indices in the primary tumor showed a significant correlation (P < 0.05), but the MCM 2 labeling index was considerably higher.

Conclusions: MCM2 may be a more reliable and useful marker than Ki-67 in assessing the growth of normal and tumor cells and in evaluating tumor aggressiveness and prognostic value in patients with esophageal SCC.