Endoscopic resection is the first-line treatment for rectal neuroendocrine tumors (NETs) measuring <1 cm and those between 1 and 2 cm in size. However, conventional endoscopic resection cannot achieve complete resection in all cases. We aimed to analyze clinical outcomes of precut endoscopic mucosal resection (EMR-P) used for the management of rectal NET.
EMR-P was used to treat rectal NET in 72 patients at a single tertiary center between 2011 and 2015. Both, circumferential precutting and EMR were performed with the same snare device in all patients. Demographics, procedural details, and histopathological features were reviewed for all cases.
Mean size of the tumor measured endoscopically was 6.8±2.8 mm.
Both, the
The increasing incidence of rectal carcinoid tumors, also called well-differentiated neuroendocrine tumors (NETs) of the rectum [
Although complete resection is essential for cure, the complete resection rate of rectal NETs observed with conventional endoscopic mucosal resection (EMR) has been found to range between 52.2% and 84.6% [
Endoscopic resection for rectal NET was performed in 218 patients at Asan Medical Center, between August 2011 and March 2015, with all procedures performed by two endoscopists (DHY and JSB). All patients were evaluated using abdominopelvic computed tomography and chest radiography before undergoing endoscopic resection to exclude metastases to regional lymph nodes and/or distant organs. Among these 218 patients, 68 were treated using conventional EMR, 37 using cap-assisted EMR, 30 using ESD, and 83 using EMR-P. The method used for endoscopic resection was based on the endoscopist’s preference/discretion. Although there was no absolute specific indication regarding the choice of method, conventional EMR was preferred if submucosal lifting was satisfactory and secure snaring of the lesion was possible. ESD was preferred for tumors measuring >1 cm in diameter. Among the 83 patients who underwent EMR-P, 11 were excluded—10 because EMR-P was performed in them for resection of remnant NET after a previous resection and one patient because of a previous history of chemoradiation therapy of the rectum. Thus, eventually 72 patients were enrolled in this study. This study was approved by the Institutional Review Board of Asan Medical Center (IRB number: 2015-0789).
EMR-P was performed using a single-channel endoscope (GIF-H260, GIF Q-260J, CF-H260AI, or CF-HQ290I; Olympus Medical Systems, Tokyo, Japan). Patients received a submucosal injection of 0.9% saline solution mixed with small amounts of 1:100,000 epinephrine and indigo carmine. Circumferential incision/precutting was performed using the tip of the snare (CAPTIVATOR or CAPTIVATOR II; Boston Scientific, Marlborough, MA, USA) to cut along a margin that was 2 mm outside the tumor. Subsequently, the snare was securely positioned in the cut groove and tightened, and the tumor was resected using electrical current (
Endoscopic
Primary outcomes were
Patient characteristics and endoscopic/histopathological results of EMR-P were summarized with mean and standard deviation (SD) for continuous variables and frequency and percentage (%) for categorical variables. Univariate analysis was performed using the χ2 test or the Fisher exact test for categorical variables and the Student’s
Mean age of the 72 patients studied was 49±13 years. Among these, 43 (59.7%) were men. All patients had been diagnosed with rectal NET incidentally during screening colonoscopy. Most rectal NETs were located at the mid-to-distal rectum at a mean distance of 5.8 cm from the anal verge. Mean size of the tumor measured endoscopically was 6.8±2.8 mm. Baseline characteristics of enrolled patients and NETs are summarized in
There were no risk factors which could predict incomplete resection (data not shown). Regarding risk factors associated with delayed bleeding, the presence of immediate bleeding was the only identifiable factor that could be correlated with delayed bleeding (
Results from this large case series showed that EMR-P was highly effective for resection of rectal NETs, as shown by the high
Although most rectal NETs are resected endoscopically, conventional EMR has been showing unsatisfactory complete resection rates, ranging between 52.2% and 84.6% [
Other modified EMR methods, including cap-assisted EMR and EMR using band ligation, have been suggested as treatment options for rectal NETs [
Our study showed that EMR-P has several advantages over other related procedures: (1) Unlike cap-assisted EMR and EMR using band ligation, which require additional accessories such as cap and ligating devices, respectively, EMR-P does not require any additional instruments because precutting is performed using the snare tip [
Two previous studies have investigated the usefulness of EMR-P for resection of rectal NET [
A strength of our EMR-P method compared to previous studies describing EMR-P [
Limitations of our study: (1) Ours was a retrospective analysis, and selection of the endoscopic resection method used was at the discretion of each endoscopist, which may have resulted in selection bias. However, selection bias was likely not very significant because selection of the endoscopic resection method was not based on any predefined absolute criteria. Additionally, EMR-P was performed in relatively difficult cases, because conventional EMR was generally used when submucosal lifting was satisfactory and secure snaring of the lesion was possible as described previously. Thus, it is possible to infer that EMR-P demonstrated a good performance, based on our study results. (2) Only 51.4% of enrolled patients underwent follow-up endoscopies, and verifying prognosis after EMR-P in this small number of cases who did undergo follow-up endoscopies was difficult. Thus, studies with a greater number of patients are necessary to confirm the accuracy of our follow-up results. (3) The median follow-up period of this study was only 12.6 months. Thus, we could not investigate patients over a long-term follow-up duration to assess local or distant recurrence. However, previous studies describe excellent long-term outcomes after endoscopic resection of rectal NETs ≤10 mm with no recurrence or metastasis noted in any patient after a median duration of 31 months, regardless of resection margin status [
In conclusion, EMR-P using the snare tip for precutting and the same snare for EMR is a highly effective method for resection of rectal NETs, showing high
Precut endoscopic mucosal resection of a rectal neuroendocrine tumor (NET). (A) A 9 mm sized rectal NET. (B) Following submucosal injection into the tumor, the tip of the snare is introduced for circumferential incision/precutting. (C) Precutting around the tumor. (D, E) Secure snaring in the precut mucosal groove. (F) A clear post-resection ulcer base is seen.
Baseline Demographic and Clinical Characteristics of Patients with Rectal NETs
Variables | All patients ( |
---|---|
Men, |
43 (59.7) |
Age (yr), mean (SD) | 49 (13.0) |
Tumor location (cm) |
5.8 (2.4) |
Endoscopically estimated size (mm), mean (SD) | 6.8 (2.8) |
Histologically measured size (mm), mean (SD) | 6.2 (2.8) |
<10 mm, |
63 (87.5) |
≥10 mm, |
9 (12.5) |
Grade of NETs, |
|
Grade 1 | 66 (91.7) |
Grade 2 | 6 (8.3) |
NET, neuroendocrine tumor; SD, standard deviation.
Measured from the anal verge.
Endoscopic and Histopathological Results of Precut Endoscopic Mucosal Resection
Variables | All patients ( |
---|---|
Endoscopic and histopathological results | |
|
71 (98.6) |
Histologically complete resection | 67 (93.1) |
Histological margin involvement | 5 (6.9) |
Lateral | 1 (1.3) |
Deep | 3 (4.3) |
Both lateral and deep | 1 (1.3) |
Lymphovascular invasion | 3 (4.3) |
Procedure-related variables | |
Resection time (min), mean (SD) | 9.0 (5.6) |
Immediate bleeding | 6 (8.3) |
Delayed bleeding | 4 (5.6) |
Perforation | 0 (0) |
Data represent
SD, standard deviation.
Predictive Factors for Delayed Bleeding
Delayed bleeding |
|||
---|---|---|---|
No ( |
Yes ( |
||
Sex | 0.14 | ||
Men, |
39 (57.4) | 4 (100) | |
Women, |
29 (42.6) | 0 (0) | |
Age (yr), mean (SD) | 48.8 (13.6) | 47.5 (9.1) | 0.85 |
Tumor location (cm), mean (SD) |
5.9 (2.4) | 4.5 (1.0) | 0.06 |
Endoscopically estimated size (cm) mean (SD) | 6.9 (2.80) | 5.0 (2.16) | 0.19 |
Histologically measured size (cm), mean (SD) | 6.4 (2.76) | 4.3 (2.87) | 0.15 |
En bloc resection, |
67 (98.5) | 4 (100) | 1.00 |
Histologically complete resection, |
63 (92.6) | 4 (100) | 1.00 |
Resection time (min), mean (SD) | 8.7 (5.07) | 12.9 (12.27) | 0.55 |
Immediate bleeding, |
4 (5.9) | 2 (50.0) | 0.03 |
SD, standard deviation.
Measured from the anal verge.
Summary of the Results of Previous Studies of Endoscopic Treatment of Rectal NETs
Method | Study | No. of patients | Size (cm) |
Complete resectio |
Procedure time (min), mean (SD) | Complications |
|
---|---|---|---|---|---|---|---|
EMR | Park et al. [ |
62 | 7.1 (2.3) | 95.2 | 71.0 | 4.2 (3.2) | Delayed bleeding: 0 (0%) |
Perforation: 1 (1.6%) | |||||||
Lee et al. [ |
28 | 5.7 (4.0) | 89.3 | 64.3 | 12.0 (12.9) | None | |
Kim et al. [ |
55 | 6.5 (3.2) | 91 | 65.5 | 5.0 (0.8) | None | |
Zhao et al. [ |
10 | N/A | 80 | 80 | 13.4 (17.13) | None | |
Huang et al. [ |
28 | 9 (2.5) | 96.55 | 82.14 | 4.2 (range, 2–10) | None | |
ESD | Park et al. [ |
31 | 6.5 (2.6) | 100 | 90.3 | 11.4 (3.7) | Delayed bleeding: 0 (0%) |
Perforation: 1 (3.2%) | |||||||
Lee et al. [ |
46 | 6.2 (3.1) | 100 | 82.6 | 18.9 (7.3) | Delayed bleeding: 0 (0%) | |
Perforation: 1 (2.2%) | |||||||
Zhao et al. [ |
10 | N/A | 100 | 100 | 24.9 (5.78) | None | |
Wang et al. [ |
25 | 12.27 (3.73) | 100 | 100 | 24.79 (4.89) | Delayed bleeding: 1 (4.0%) | |
Perforation: 2 (8.0%) | |||||||
Cheung et al. [ |
17 | 7.53 (1.94) | 100 | 88.2 | 20.2 (12.6) | Delayed bleeding: 0 (0%) | |
Perforation: 1 (5.9%) | |||||||
EMR-C | Zhao et al. [ |
10 | N/A | 100 | 100 | 5.2 (0.78) | None |
Wang et al. [ |
30 | 10.35 (2.95) | 83.3 | 70 | 9.52 (2.14) | None | |
EMR-L | Mashimo et al. [ |
61 | 6.4 (2.4) | N/A | 95.2 | N/A | Delayed bleeding: 1 (1.6%) |
Perforation: 0 (0%) | |||||||
Kim et al. [ |
45 | 5.8 (2.4) | 100 | 93.3 | 4.8 (0.9) | Delayed bleeding: 1 (2.2%) | |
Perforation: 0 (0%) | |||||||
EMR-P | Huang et al. [ |
31 | 9 (2.5) | 100 | 96.7 | 7.6 (range, 5–13) | None |
Cheung et al. [ |
16 | 6.63 (1.99) | 87.5 | 81.2 | 9.69 (3.61) | Delayed bleeding: 0 (0%) | |
Perforation: 1 (6.3%) | |||||||
This study | 72 | 6.2 (2.8) | 98.6 | 93.1 | 9.0 (5.6) | Delayed bleeding: 4 (5.6%) | |
Perforation: 0 (0%) |
Data reported as (%), mean (SD) or median (range).
NET, neuroendocrine tumor; SD, standard deviation; EMR, endoscopic mucosal resection; ESD, endoscopic submucosal dissection; EMR-C, cap-assisted EMR; EMR-L, EMR using band ligation; EMR-P, precut endoscopic mucosal resection; N/A, not available.
Histologically measured size.
Delayed bleeding and perforation.