Transanal endoscopic microsurgery in very large and ultra large rectal neoplasia

Transanal endoscopic microsurgery (TEM) has become the treatment of choice for benign rectal lesions and early rectal cancer (T1). The size classification of rectal polyps is controversial. Some articles define giant rectal lesions as those larger than 5 cm, which present a significantly increased risk of complications. The aim of this study was to evaluate the feasibility of TEM in these lesions.

An observational descriptive study with prospective data collection evaluating the feasibility of TEM in large rectal adenomas was performed between June 2004 and September 2018. Patients were assigned to one of the three groups according to size: < 5 cm, very large (5-7.9 cm) and ultra-large (≥ 8 cm). Descriptive and comparative analyses between groups were performed.

TEM was indicated in 761 patients. Five hundred and seven patients (66.6%) with adenoma in the preoperative biopsy were included in the study. Three hundred and nine out of 507 (60.9%) tumors < 5 cm, 162/507 (32%) very large tumors (5-7.9 cm) and 36/507 (7.1%) ultra-large tumors (≥ 8 cm) were reviewed. Morbidity increased with tumor size: 17.5% in tumors < 5 cm, 26.5% in those 5-7.9 cm, and 36.1% in those > 8 cm. Peritoneal perforation, fragmentation, free margins and stenosis were also more common in very large and ultra-large tumors (p < 0.001). There were no statistical differences between the groups in the definitive pathology (p = 0.38).

TEM in these large tumors is associated with higher rates of morbidity, peritoneal perforation, free margins and stenosis. Although these tumors do not require total mesorectal excision and are eligible for TEM, the surgery must be carried out by experienced surgeons.