Editorial
Copyright ©2010 Baishideng. All rights reserved.
World J Gastrointest Surg. May 27, 2010; 2(5): 153-156
Published online May 27, 2010. doi: 10.4240/wjgs.v2.i5.153
Treatment of colorectal carcinoids: A new paradigm
Tsuyoshi Konishi, Toshiaki Watanabe, Hirokazu Nagawa, Masatoshi Oya, Masashi Ueno, Hiroya Kuroyanagi, Yoshiya Fujimoto, Takashi Akiyoshi, Toshiharu Yamaguchi, Tetsuichiro Muto
Tsuyoshi Konishi, Masatoshi Oya, Masashi Ueno, Hiroya Kuroyanagi, Yoshiya Fujimoto, Takashi Akiyoshi, Toshiharu Yamaguchi, Tetsuichiro Muto, Department of Gastroenterological Surgery, Cancer Institute Hospital, Tokyo 135-8550, Japan
Tsuyoshi Konishi, Hirokazu Nagawa, Department of Surgical Oncology, University of Tokyo, Tokyo 113-8655, Japan
Toshiaki Watanabe, Department of Surgery, Teikyo University School of Medicine, Tokyo 173-8605, Japan
Author contributions: Konishi T drafted the manuscript, collected and interpreted the data; Watanabe T, Nagawa H, Yamaguchi T and Muto T critically revised and supervised the study; Oya M, Ueno M, Kuroyanagi H, Fujimoto Y and Akiyoshi T collected and interpreted the data.
Correspondence to: Dr. Tsuyoshi Konishi, MD, Department of Gastroenterological Surgery, Cancer Institute Hospital, 3-10-6 Ariake, Koto-ku, Tokyo 135-8550, Japan. tsuyoshikonishi@pop07.odn.ne.jp
Telephone: +81-3-3520-0111 Fax: +81-3-3570-0343
Received: December 26, 2009
Revised: March 2, 2010
Accepted: March 9, 2010
Published online: May 27, 2010
Abstract

It is often difficult to evaluate the grade of malignancy and choose an appropriate treatment for colorectal carcinoids in clinical settings. Although tumor size and depth of invasion are evidently not enough to stratify the risk of this rare tumor, the present guidelines or staging systems do not mention other clinicopathological variables. Recent studies, however, have shed light on the impact of lymphovascular invasion on the outcome of colorectal carcinoids. It has been revealed that the presence of lymphovascular invasion was among the strongest risk factors for metastasis along with tumor size and depth of invasion. Furthermore, tumors smaller than 1 cm, within submucosal invasion and without lymphovascular invasion, carry minimal risk for metastasis with 100% 5-year survival in the studies from Japan as well as from the USA. This would suggest that these tumors could be curatively treated by endoscopic resection or transanal local excision. On the other hand, colorectal carcinoids with either lymphovascular invasion or tumor size larger than 1 cm carry the risk for metastasis equivalent to adenocarcinomas. Therefore, it should be emphasized that histological examination of lymphovascular invasion is mandatory in the specimens obtained by endoscopic resection or transanal local excision, as this would provide useful information for determining the need for additional radical surgery with regional lymph node dissection. Although the present guidelines or TNM staging system do not mention the impact of lymphovascular invasion, this would be among the next promising targets in order to establish better guidelines and staging systems, particularly in early-stage colorectal carcinoids.

Keywords: Lymphovascular invasion; Neuroendocrine tumor; Carcinoid; Colorectal cancer