Endoscopic treatment of early rectal cancer after multiple surgical approaches: endoscopic intermuscular dissection to the rescue.
Authors: Lima Pedro André , Mendes Raquel R. , Barreiro Pedro , Mendo Rui , Chagas Cristina 
Published: February 2025

A 68-year-old woman with a prior history of rectal adenocarcinoma (T3N1M0) in 2007, treated with neoadjuvant chemoradiotherapy, followed by anterior rectal resection (R0 resection) in Belgium, lost follow-up after returning to Portugal. In 2022, a surveillance colonoscopy revealed an extensive polypoid lesion in the middle and distal rectum, without suggestive signs of deep submucosal invasion (JNET 2a). Biopsies revealed a tubulovillous adenoma with low grade dysplasia. Staging with pelvic magnet resonance imaging (MRI) suggested a rectal cancer cT3bN0. After a multidisciplinary discussion, due to the endoscopic findings, lesion resection via Transanal Minimally Invasive Surgery (TAMIS) was proposed. However, TAMIS only achieved piecemeal resection, with a non-evaluable base of insertion (Rx). Histopathology revealed a tubulovillous adenoma with low-grade dysplasia.
In 2023, a surveillance colonoscopy showed, in the lower rectum, a 4 cm residual lesion of the mixed granular LST type, involving 70% of the rectum circumference, associated with pseudodiverticula and fibrotic areas, continuing to show no signs of deep submucosal invasion (JNET2A) - figure 1a and 1b.
She was then referred to our center for endoscopic resection by endoscopic submucosal dissection (ESD). The procedure was performed with anesthetic support, using 1.5 mm Flush Knife® (Fujifilm). During the procedure, extensive areas of severe fibrosis were identified, as well as multiple surgical clips (figure 2), making it impossible to identify a clear dissection plane of the submucosa. Due to these facts, segmental endoscopic intermuscular dissection (EID) was performed to achieve en bloc resection (figure 3). During the procedure, two perforations (2 and 3 mm) were identified that were successfully treated with TTS clips. The procedure lasted 114 minutes, and the patient was discharged 24 hours later without complications under antibiotics. Histopathology showed a tubulovillous adenoma with low-grade dysplasia, with focal cauterized tissue at the lateral margin (HMx). Endoscopic re-evaluation was performed six months later, showing no evidence of local recurrence.

ESD, EID and TAMIS are effective and safe techniques for the treatment of early rectal cancers. Frequently, ESD is performed to achieve en bloc resections allowing perfect histopathological assessment and a lower risk of recurrence. However, in cases with severe and extensive fibrosis, commonly after endoscopic or surgical approaches, a clear identification of the submucosal plane during ESD is frequently impossible. In these cases, in the rectum, EID can be considered as a rescue technique. This technique involves the dissection of the tissue between the muscular layers of the rectal wall (intermuscular space) to facilitate better access and ensure complete resection of the lesion, being an alternative and attractive endoscopic resection technique.
The key point is that endoscopic resection remains a valuable and safe procedure for managing particularly challenging rectal lesions, especially those with local recurrence after endoscopic or surgical approaches and those with severe submucosal fibrosis. In these cases, EID should be considered to achieve R0 resection and reduce the local recurrence risk. This case further highlights the importance of appropriate endoscopic staging, as MRI staging often overstages early rectal neoplasms, potentially leading to increased risk of inappropriate therapeutic options.