Endoscopic intermuscular dissection of early rectal cancer

Introduction Recent data show that the depth of submucosal invasion is not a risk factor of lymph node metastasis in colorectal cancer. Thus, endoscopic resection of cancers with deep submucosal invasion is possible. This study aims to evaluate the role of endoscopic intermuscular dissection (EID) in early rectal cancer. Method This study includes the first 12 cases of EID performed in Sweden during 2023-2024. All patients included had macroscopic suspicion of deep submucosal invasion in the rectum. EID is defined by endoscopic resection between the circular and longitudinal part of the muscularis propria. Study outcomes were the percentages of technical success, R0 resection, curative resection, and adverse events. Result 12 patients underwent EID with suspicious macroscopic cancer. En bloc resection was achieved in all (12/12) patients. Two lesions turned out to be benign, nine cases were T1, and one was a T2 cancer. The T2 case resulted in non-radical resection. R0 resection rate was 100% in patients with T1 cancer. Seven of nine cases with T1 cancer had deep submucosal invasion (Sm2/3). When deep submucosal invasion was not considered a high risk factor curative resection rate was 56% (5/9) in all T1 cancers. Two patients experienced pain and fever after the procedure and were treated conservatively with antibiotics. Discussion EID appears to be feasible in patients with early rectal cancer and deep submucosal invasion.