Endoscopic Intermuscular Dissection for Deep Submucosal Invasion in Rectal Cancer

Endoscopic submucosal dissection (ESD) for T1 rectal cancer can leave positive margins, particularly for lesions invasive to the middle or deep thirds of the submucosa. One method to improve outcomes is to lower the dissection plane to the space between the circular and longitudinal muscles, so-called endoscopic intermuscular dissection (EID). 

This report describes 67 patients who underwent EID for rectal cancer, median lesion size 25 mm, with suspected deep submucosal invasion. En bloc resection was achieved in 64 patients. The procedure was aborted in 3 patients due to tumor invasion in the intermuscular plane. EID was achieved in 56 patients, and 8 had a partial full-thickness resection, which was closed with clips or sutures. The mean procedure time was 110 minutes. R0 resection was achieved in 54 of 67 patients, and curative resection was successful in 30 patients (45%). 

The R0 resection rate for T1 cancers with SM2 or SM3 depth of invasion was 90%. Overall adverse events occurred in 8 patients (12%) and included rectal pain and inflammatory changes without fluid collections. In addition, 1 patient experienced rectal bleeding, and 1 patient had stenosis requiring dilation.