Electrocautery snare resection stimulates cellular proliferation of residual colorectal tumor - An increasing gene expression related to tumor growth

PURPOSE: Recently, endoscopic mucosal resection has been performed commonly for colorectal tumors. However, incomplete endoscopic mucosal resection pr oduces a residual tumor that grows rapidly. The aim of this study was to cl arify the characteristics of the residual tumor using the nude mouse model. METHODS: Human colon cancer cells (colo201 or colo320DM) were implanted su bcutaneous into nude mice. We then removed more than one-half of the tumor with an electrocautery snare or a surgical knife, and compared the tumor gr owth rate with that of control tumors. Before and after resection, we exami ned the Ki-67 labeling index of the tumors with an immunohistochemical assa y and mRNA expression for epidermal growth factor receptor, vascular endoth elial growth factor, and transforming growth factor alpha. RESULTS: Residua l tumors showed a higher growth rate ill tumor volume than control tumors u sing both methods (electrocautery snare and surgical knife). Colo201 groups showed a higher total volume change per day than colo320DM groups after re section. Furthermore, these tumors also showed a higher Ki-67 labeling Inde x, and a stronger epidermal growth factor receptor and transforming growth factor alpha mRNA expression than primary and control tumors in the colo201 implanted groups. There was no significant difference in vascular endothel ial growth factor mRNA expression between groups implanted with colo201 or colo320DM. CONCLUSION: Our results suggest that residual tumors caused by i ncomplete endoscopic mucosal resection may have a higher growth potential t han the tumors before resection.