Outcomes of endoscopic submucosal dissection for different subtypes of colorectal laterally spreading tumors

Abstract

[ Abstract ] Objective To investigate the clinicopathological features of specific subtypes of laterally spreading tumor （LST） and assess the outcomes of endoscopic submucosal dissection （ESD） based upon dif- ferentiation status. Methods A total of 174 cases of colorectal LST, treated with ESD between January 2007 and April 2011, were divided into granular type （LST-G） and non-granular type （LST-NG） , and fur- ther divided into 4 subtypes, including homogeneous granular, nodular mixed, fiat elevated and pseudo-de- pressed types. Clinicopathologieal data and ESD parameters were compared between the four subtypes. Re- sults Nodular mixed tumors were larger than homogeneous tumors, needed longer operation time and were more frequently seen in malignant transformation, high grade intraepithelial neoplasm （ HGIN ） as well as submucosal invasive cancer. So were pseudo-depressed tumors compared with fiat elevated ones （P 〈 0. 01 ）. There was no significant difference between LST-G and LST-NG in the parameters of ESD including en bloc resection rate, complete resection rate and complete cure resection rate. The complications tended to be more frequent in nodular mixed tumors （bleeding rate： 4. 6%; perforation rate： 3.5% ） and pseudo-depressed tumors （bleeding rate： 11.1% ; perforation rate 11.1% ）, but there was no severe complication in either homogeneous tumors or fiat elevated tumors. One recurrent pseudo-depressed tumor was found 6 months after ESD treatment. Conclusion The degree of technical difficulty appears higher for nodular mixed and pseu- do-depressed tumors than for homogeneous and fiat elevated tumors, as is shown in procedure time and com- plication rate. ESD for these two subtypes should better be performed by experienced endoscopists. Accurate differentiation of the LST lesions is needed in basic and clinical research. Key words: Colorectal neoplasms; Isoforms; Laterally spreading tumor; Endoscopic submucosal dissection