Endoscopic transmural resection as an alternative to colorectal surgery after high-risk (non-curative) endoscopic resection.

Endoscopic full-thickness resection (eFTR) is an emerging technique that enables effective and safe management of complex colorectal lesions. The full-thickness resection device (FTRD®, Ovesco, Germany) has primarily been used for non-exposed transmural resection of challenging subepithelial or epithelial lesions, where conventional methods may be limited. This technique represents an alternative to surgery in selected patients, and its applications are rapidly expanding. In recent years, eFTR has been described as an alternative to surgery for scars aiming to exclude residual tumors after non-curative endoscopic resection. We present a case of a 41-year-old woman with Lynch syndrome (dMLH1) with rectal adenocarcinoma at the age of 20 underwent anterior resection of the rectum and adjuvant chemoradiotherapy. At the age of 39, during endoscopic surveillance, she presented with a suspicious lesion (Paris 0-Is+IIa, NICE2, JNET2B) measuring 16mm in the hepatic angle, and underwent en bloc endoscopic mucosal resection (EMR). Histopathological analysis revealed a low-grade invasive adenocarcinoma with lymphoid stroma with deep invasion of the submucosa and resection margin involvement (vertical R1). After a multidisciplinary team discussion, complementary surgery was proposed but the patient refused, opting for close endoscopic and imaging surveillance. Two subsequent colonoscopies plus computed tomography (CT) scans showed no signs of macro or microscopic residual or recurrent tumor, even after extensive biopsies of the colonic scar. However, a CT scan 20months post-resection showed a de novo 2cm thickening of the parietal wall in the hepatic angle, consistent with the location of the previous endoscopic resection. Suspecting deep parietal tumor recurrence without superficial endoscopic findings, a transmural endoscopic resection using FTRD® of the EMR scar was performed, whose histology revealed no transparietal tumor recurrence.