T1 colorectal cancer management in the era of minimally invasive endoscopic resection

Table 1 Common endoscopic techniques, specific applications, and associated outcomes

Endoscopic technique	Application in T1 CRC	Outcomes	Advantages	Disadvantages
EMR	Recommended for lesions < 20 mm due to risk of piecemeal resection	En-bloc resection: 85.2%[44]; R0 resection: 83.9%[44]	Widely available, efficient, less resource intensive, high technical success in expert centers	Limited en-bloc resection rate with increasing size
ESD	Recommended for T1 CRC without signs of deep submucosal invasion	En-bloc resection: 98.7%[45]; R0 resection: 97.4%[45]	High en-bloc resection, technical success, and clinical success rate	Resource intensive and requires specific training
EFTR	Primary and secondary resection of T1 CRC	Technical success: 87.0%[48]; R0 resection: 85%[48]	High en-bloc and R0 resection rate, particularly for deep invasion and submucosal fibrosis	Depends on local expertise and technology availability. Risk of appendicitis and heightened risk of delayed perforation
TES: TEM, TAMIS	Rectal T1 CRC	TEM: En-bloc resection: 97.0%[57]; R0 resection: 93.0%[57]	Full thickness-resection. High en-bloc and R0 resection rate, particularly for deep invasion	For rectal lesions only. Resource intensive and requires specific training. May affect planes for completion total mesorectal excision

EFTR: Endoscopic full-thickness resection; EMR: Endoscopic mucosal resection; ESD: Endoscopic submucosal dissection; TAMIS: Transanal minimally invasive surgery; TEM: Transanal endoscopic microsurgery; TES: Transanal endoscopic surgery; CRC: Colorectal cancer.

Table 2 Pre-resection optical evaluation of colorectal polyps

Optical evaluation	Corresponding histopathology	Suspicion of malignancy	Recommended management
NICE I, JNET I	Serrated Polyp	Low	Endoscopic polypectomy, EMR, CSR
NICE II, JNET II	Adenomatous Polyp	Low	If suspected superficial invasion: en-bloc resection by EMR1, ESD, EFTR, TES2 If suspected deep invasion: surgery or multidisciplinary review
JNET IIB	Superficial submucosal invasion	Yes, superficial
NICE III, JNET III	Deep submucosal invasion	Yes, deep
Paris 0-IIa+Is granular lesions in distal colorectum	Covert submucosal invasion	Yes
Paris 0-Is/0-IIa+Is nongranular lesions in distal colorectum	Covert submucosal invasion	Yes

¹Applicable for lesions < 20 mm.

²Applicable to rectal lesions.

CSR: Cold snare resection; EFTR: Endoscopic full-thickness resection; EMR: Endoscopic mucosal resection; ESD: Endoscopic submucosal dissection; JNET: Japan NBI Expert Team; NICE: NBI International Colorectal Endoscopic; TES: Transanal endoscopic surgery.

Table 3 T1 Colorectal cancer post-resection algorithm

	High-risk T1 CRC	Low-risk T1 CRC
High Risk Histopathology Features (lymphovascular invasion, tumor budding, poor differentiation, deep submucosal invasion (≥ 1000 µm)1, positive resection margin)	Presence of one or more histopathology features	Absence of all high-risk histopathology features
Resection status	Non-curative	Curative
Recommended management	Adjuvant surgery or multidisciplinary review	Surveillance

¹Deep submucosal invasion may be considered a low-risk feature in isolation.

CRC: Colorectal cancer.

Table 4 T1 Colorectal cancer surveillance

Guideline	First surveillance		Subsequent surveillance
Japanese Society for Cancer of the Colon and Rectum 2019[10]	Colonoscopy at 6-12 months		No specific comment
European Society of Gastrointestinal Endoscopy 2019[11]	Colonoscopy at 3-6 months		1, 3, and 5 yr
American Gastroenterology Association 2021[60]	Colon	Colonoscopy at 3-6 months	6 months and 1 yr
	Rectum	Flexible sigmoidoscopy at 3-6 months and colonoscopy at 1 yr	Flexible sigmoidoscopy every 6 months up to 5 yr, with concomitant EUS or pelvic magnetic resonance imaging every 3-6 months for 2 yr, then every 6 months to complete 5 yr. May consider CT chest, abdomen, and pelvis for 3-5 yr

EUS: Endoscopic ultrasound; CT: Computed tomography.

Table 5 Emerging treatment options for T1 colorectal cancer

Emerging technique	Description	Application in T1 CRC	Outcomes and evidence
Endoscopic submucosal dissection for suspected focal deep submucosal invasion	En-bloc endoscopic resection for lesions with optical evaluation suggesting focal deep submucosal invasion	For patients preferring or only eligible for conservative management, who would otherwise be referred to first-line surgery	Retrospective study of colorectal neoplasia with focal deep invasion found R0 resection of 77% and curative resection in 27%[62]
Endoscopic intermuscular dissection	Dissection between inner (circular) and outer (longitudinal) muscularis propria	For rectal cancers, particularly with a concern for deep submucosal invasion	Prospective cohort study of T1 rectal cancer demonstrated technical success of 96%, R0 resection of 81%, and curative resection of 45%[63]
Colonoscopy-assisted laparoscopic wedge resection	Laparoscopic resection and closure of colonic lesions under direct intraluminal endoscopic guidance	For colon cancers, particularly with deep submucosal invasion	Case series of patients with high grade dysplasia or T1 colon cancer demonstrated R0 resection of 89%[67]
Neoadjuvant and adjuvant chemoradiation1	Use of chemoradiation or chemotherapy alone before or after resection to increase efficacy of local excision1	For downstaging early rectal cancer or for prevention of recurrence following local excision of high risk T1 CRC	NEO trial (phase II) of early rectal cancer showed 57% downstaging, 79% organ preservation, and 90% 2-yr local regional relapse free survival[73]. Systematic review subgroup analysis of T1 CRC treated with adjuvant chemoradiation showed local recurrence rate of 3.9%[75]

¹Use prior to/followed by local excision with transanal endoscopic surgical techniques.

CRC: Colorectal cancer.