Electrocautery snare resection stimulates cellular proliferation of residual colorectal tumor: an increasing gene expression related to tumor growth.
OBJECTIVE
Recently, endoscopic mucosal resection has been performed commonly for colorectal tumors. However, incomplete endoscopic mucosal resection produces a residual tumor that grows rapidly. The aim of this study was to clarify the characteristics of the residual tumor using the nude mouse model.


METHODS
Human colon cancer cells (colo201 or colo320DM) were implanted subcutaneous 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 growth rate with that of control tumors. Before and after resection, we examined the Ki-67 labeling index of the tumors with an immunohistochemical assay and mRNA expression for epidermal growth factor receptor, vascular endothelial growth factor, and transforming growth factor alpha.


RESULTS
Residual tumors showed a higher growth rate in tumor volume than control tumors using both methods (electrocautery snare and surgical knife). Colo201 groups showed a higher total volume change per day than colo320DM groups after resection. Furthermore, these tumors also showed a higher Ki-7 labeling index, 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 endothelial growth factor mRNA expression between groups implanted with colo201 or colo320DM.


CONCLUSIONS
Our results suggest that residual tumors caused by incomplete endoscopic mucosal resection may have a higher growth potential than the tumors before resection.
Kunihiro
M
M
First Department of Internal Medicine, Hiroshima University School of Medicine, Japan.
Tanaka
S
S
Haruma
K
K
Kitadai
Y
Y
Yoshihara
M
M
Sumii
K
K
Kajiyama
G
G
Nishiyama
M
M
D000818:Animals; D002455:Cell Division; D003113:Colonoscopy; D015179:Colorectal Neoplasms / Q000235:genetics / Q000473:pathology / Q000601:surgery*; D004564:Electrocoagulation; D015972:Gene Expression Regulation, Neoplastic; D006133:Growth Substances / Q000096:biosynthesis / Q000235:genetics; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D018365:Neoplasm, Residual; D012333:RNA, Messenger / Q000096:biosynthesis; D014183:Transplantation, Heterologous
D006133:Growth Substances; D012333:RNA, Messenger