Endoscopic treatment and management of rectal neuroendocrine tumors less than 10 mm in diameter

Table 1 Comparison of different endoscopic and surgical techniques

Technique	Description	Advantages	Risks	Percentage of R0 resection and complication
Transanal resection	Removes the tumor at a higher position	Ensures a deep removal in the muscularis mucosa	For rNETs less than 10 mm, the risk is greater than the benefit	96.8% R0 resection; urinary tract infection, subcutaneous emphysema, urinary tract infection[56]
Transanal endoscopic microsurgery (TEMS)	A localized resection under a laparoscopic view through the anus	Direct and complete removal of the lesion and the resection wound is fully and surgically sutured under direct vision	Expensive fees for the operation and anesthesia; postoperative fecal incontinence	92.3% R0 resection, no complication[57]
Traditional EMR	Mucosal resection by electro-coagulation	Fast and convenient	Incomplete resection; crushed wound affects the pathological evaluation	50% R0 resection, 7.1% complications[37]
Cap-assisted EMR (EMR-C)	Attracts the tumor to a cap and removes it using a crescent snare	Effective treatment, short operation duration	The depth of the vertical resection margin needs fully guaranteed	94.1% R0 resection 8.8% intraprocedural bleeding[58]
Dual-channel endoscope (EMR-D)	One channel delivers the snare and the other delivers the forceps to lift the lesion	Simple, easy-to-learn, and effective; ensuring the vertical depth of the resection by lifting	Requires dual-instrument channel endoscopy	86.3% R0 resection, minor bleeding (1/44)[36]
EMR with a ligation device (EMR-L)	Injection and rubber ring to form a pseudo-polyp, retracting the snare under it and resect the tumor	More fully ensures the vertical depth of tumor resection; resects without destroying or deforming the tumor	Inadequacy for large tumors	89.5%[37], 99.4%[59], 86.2%[55] R0 resection, 0.6% perforation and 6.1% delayed bleeding[59]
Underwater EMR (UEMR)	To float the tumor by the buoyancy of the water without submucosal injection before electro-coagulating resection	Ensures a clean resection margin and safe removal of rNETs	Electrocoagulation damages the edge of the specimen	83% R0 resection, no complication[60]
ESD	Submucosal dissection	Lower recurrence rate	Perforation and bleeding; lasts for a long time and requires highly experienced surgeons	94.7%[37], 100%[47], 92%[50], 97%[55], 88.4%[36], 86.1%[32], 11.5% minor bleeding[36], 2.5% adverse events[32]

ESD: Endoscopic submucosal dissection; EMR: Endoscopic mucosal resection; rNETs: Rectal neuroendocrine tumors.