Underwater endoscopic mucosal resection: a new endoscopic method for resection of rectal neuroendocrine tumor grade 1 (carcinoid) ≤ 10 mm in diameter

Treatment strategy and post-treatment management of colorectal neuroendocrine tumor

Following the increase in colorectal neuroendocrine tumors (NETs), there is a consequent increase in the importance of their appropriate treatment and post-treatment management. It is widely accepted that colorectal NETs sized ≥20 mm and those with muscularis propria invasion are indicated for radical surgery, and those sized <10 mm without the invasion are indicated for local resection. No consensus has been reached regarding the treatment strategy for those sized 10-19 mm without the invasion. Endoscopic resection has become a primary option for the local resection of colorectal NETs. For rectal NETs sized <10 mm, modified endoscopic mucosal resection, such as endoscopic submucosal resection with ligation device and endoscopic mucosal resection with a cap-fitted panendoscope, seems favorable because of its ability to achieve a high R0 resection rate, safety, and convenience. Endoscopic submucosal dissection can also be helpful for these lesions; however, this procedure may be more effective for large lesions or those in the colon. Management following local resection of colorectal NETs is based on the pathological evaluation of factors associated with metastasis, including tumor size, invasion depth, tumor cell proliferative activity (NET grading), presence of lymphovascular invasion, and resection margins. There remain unclear issues in managing cases with NET grading ≥2, positive lymphovascular invasion, and positive resection margins following local resection. In particular, there is confusion regarding managing positive lymphovascular invasion because positivity has become remarkably high with the increased use of the immunohistochemical/special staining. Further evidence based on long-term clinical outcomes is required to address these issues.

Clinical Value of Clip-and-Snare Assisted Endoscopic Submucosal Resection in Treatment of Rectal Neuroendocrine Tumors

Introduction

The aim of the study was to introduce a new endoscopic technology, clip-and-snare assisted endoscopic submucosal resection (CS-ESMR), for treatment of rectal neuroendocrine tumors (NETs) and then to investigate the therapeutic value of CS-ESMR.

Methods

In this retrospective study, 67 patients who underwent endoscopic treatment of rectal NETs from March 2017 to December 2021 were analyzed. According to the endoscopic resection methods (endoscopic mucosal resection [EMR], CS-ESMR, and endoscopic submucosal dissection [ESD]), the cases were divided into CS-ESMR group (27 cases), ESD group (31 cases), and EMR group (9 cases). The pathological R0 resection rate and the incidence of adverse events (bleeding and perforation) were compared among the three groups.

Results

There was a significant difference about the pathological R0 resection between the CS-ESMR group and the EMR group and between the CS-ESMR group and the ESD group (both p < 0.05). Compared with ESD group, the procedure time, intraoperative bleeding, and the cost of CS-ESMR group are significantly decreased (p < 0.001, p < 0.05, p < 0.001, respectively).

Conclusion

CS-ESMR may be a safe and effective treatment for rectal NETs with a diameter of less than 10 mm, without muscularis propria invasion and metastasis.

European Neuroendocrine Tumor Society (ENETS) 2023 guidance paper for colorectal neuroendocrine tumours

This ENETS guidance paper, developed by a multidisciplinary working group, provides an update on the previous colorectal guidance paper in a different format. Guided by key clinical questions practical advice on the diagnosis and management of neuroendocrine tumours (NET) of the caecum, colon, and rectum is provided. Although covered in one guidance paper colorectal NET comprises a heterogeneous group of neoplasms. The most common rectal NET are often small G1 tumours that can be treated by adequate endoscopic resection techniques. Evidence from prospective clinical trials on the treatment of metastatic colorectal NET is limited and discussion of patients in experienced multidisciplinary tumour boards strongly recommended. Neuroendocrine carcinomas (NEC) and mixed neuroendocrine non-neuroendocrine neoplasms (MiNEN) are discussed in a separate guidance paper.

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

Rectal neuroendocrine tumors (rNETs) measuring less than 10 mm in diameter are defined as small rNETs. Due to the low risk of distant invasion and metastasis, endoscopic treatments, including modified endoscopic mucosal resection, endoscopic submucosal dissection, and other transanal surgical procedures, are effective. This review article proposes a follow-up plan according to the size and histopathology of the tumor after operation.

Multiple ligation-assisted endoscopic submucosal resection combined with endoscopic ultrasonography: a novel method to treat rectal neuroendocrine tumors

OBJECTIVE

The first choice of treatment for rectal neuroendocrine tumors (R-NETs) 10 mm in size is endoscopic resection, there is still controversy concerning the optimal endoscopic treatment for resecting R-NETs. This study evaluated the efficacy and safety of multiple ligation-assisted endoscopic submucosal resection combined with endoscopic ultrasonography (EMR-MLUS) for R-NETs.

METHODS

We retrospectively analyzed the data of 62 patients with R-NETs ≤10 mm in size who underwent EMR-MLUS or ligation-assisted endoscopic submucosal resection combined with endoscopic ultrasonography (EMR-LUS) between May 2019 and April 2022, including tumor characteristics, endoscopic complete resection, pathological complete resection, the procedure time, adverse events, and follow-up were compared between the two groups of patients.

RESULTS

Of the 62 patients, 19 underwent EMR-MLUS and 43 underwent EMR-LUS. The endoscopic morphology of lesions was statistically different between group EMR-MLUS and group EMR-LUS ( P = 0.015), and most of them were flat and slightly raised lesions in group EMR-MLUS. Although the pathological complete resection rate was slightly higher in the EMR-MLUS group than in the EMR-LUS group (94.74% vs. 90.70%; P = 0.290), the endoscopic complete resection rate was high in both groups. Involvement of the lateral resection margin was found four cases in the ESMR-LUS group; one case of deep resection margin involvement in the EMR-MLUS group. The mean procedure time was longer in the EMR-MLUS group than in the EMR-LUS group (12.79 ± 1.01 min vs. 11.08 ± 1.89 min; P = 0.041). In group EMR-LUS, there were two cases of immediate bleeding; in group EMR-MLUS, one case of perforation, all of them were successfully treated by endoscopy. No recurrence, progression, or metastasis was found in all patients.

CONCLUSION

EMR-MLUS is a safe and effective technique that could be considered when removing small rectal NETs, especially flat and slightly raised lesions.

Underwater endoscopic mucosal resection for rectal neuroendocrine tumors (with videos): a single center retrospective study

BACKGROUND

Underwater endoscopic mucosal resection (UMER) is a new method of endoscopic resection to completely remove the lesion without submucosal injection. But few attempts have been carried out for rectal neuroendocrine tumors (rectal NETs).

METHODS

We retrospectively investigated data on the tumor characteristics and outcomes of patients with ≤ 10 mm rectal NETs who underwent UEMR or endoscopic submucosal dissection (ESD) from January 2019 to June 2021 in our institute.

RESULTS

The endoscopic resection rate was 100% in both UEMR and ESD groups. The histological complete resection rate of the UEMR group (95.5%) was lower than that of the ESD group (96.4%) with no significant difference. The average operation time, hospitalization time and operation cost of UEMR group were less than those of ESD group (P < 0.05). The incidence of postoperative abdominal pain and abdominal distention in the UEMR group was lower than that in the ESD group (P < 0.05). There was no significant difference in the incidence of delayed bleeding and perforation between the two groups. There was no local recurrence or distant metastasis in the two groups during the follow-up period.

CONCLUSIONS

Both the UEMR and ESD can effectively treat ≤ 10 mm rectal NETs with invasion depth confined to the mucosa and submucosa. UEMR is superior to ESD in operation time, hospitalization time, operation cost, postoperative abdominal pain and abdominal distention.

Underwater Endoscopic Mucosal Resection of Small Rectal Neuroendocrine Tumors

Background and Study Aims

The resection strategy for rectal neuroendocrine tumors (NET) < 10 mm is not uniform. We compared the utility of underwater endoscopic mucosal resection (UEMR) to endoscopic submucosal resection with a ligation device (ESMR-L) to resect rectal NETs.

Patients and Methods

Patients with rectal NET < 10 mm treated with UEMR or ESMR-L were included. Their medical records were retrospectively reviewed.

Results

Thirty-two patients were divided into a UEMR group (n = 7) and an ESMR-L group (n = 25). Histopathological diagnosis of NET by biopsy was known before resection in 43% (3/7) in the UEMR group and 68% (17/25) in the ESMR-L group, (p = 0.379). UEMR was performed on an outpatient basis for all patients, and 92% of ESMR-L (23/25) were performed as inpatient procedures (p < 0.001). The procedure time was significantly shorter in the UEMR group than in the ESMR-L group [median (IQR), min, 6 (5–8) vs. 12 (9–14), p = 0.002]. En bloc resection and R0 resection rates were 100% in both groups. Pathological evaluations were predominantly NET G1 in both groups (UEMR: 7/7, 100% and ESMR-L: 23/25, 92%). Two patients in the ESMR-L group developed delayed bleeding, controlled by endoscopic hemostasis. Device costs were significantly higher in the ESMR-L group than the UEMR group by approximately US$180 [median (IQR), $90.45 (83.64–108.41) vs. $274.73 (265.86–292.45), P < 0.001].

Conclusion

UEMR results in similar resection quality with shorter procedure time and lower costs compared to ESMR-L. We recommend UEMR for the resection of rectal NET < 10 mm.

Underwater endoscopic mucosal resection for colorectal lesions: Can it be an “Underwater” revolution?

Underwater endoscopic mucosal resection (UEMR) is a newly developed technique for the removal of colorectal, duodenal, esophageal, gastric, ampullary, and small intestinal lesions. We performed a PubMed literature search for articles reporting UEMR outcomes for colorectal polyps. Four randomized controlled trials, nine non‐randomized prospective trials, 16 retrospective studies, and 27 case reports were selected for assessment of the efficacy and safety of UEMR. We summarized the therapeutic outcomes of UEMR in each category according to the lesion characteristics [small size (<10 mm), intermediate size (10–19 mm), large size (≥20 mm), recurrent lesion, and rectal neuroendocrine tumor], and calculated the incidence of adverse events among the included articles. As the treatment outcomes for small polyps appeared similar between UEMR and conventional endoscopic mucosal resection (CEMR), UEMR can be a standard procedure for small colorectal polyps suspicious for high‐grade dysplasia to avoid incomplete removal of occult invasive cancer by cold snare polypectomy. As UEMR showed satisfactory outcomes for intermediate‐size lesions and recurrent lesions after endoscopic resection, UEMR can be a standard procedure for these lesions. Regarding large lesions and rectal neuroendocrine tumors, comparisons of UEMR with current standard methods for them were lacking, and further investigations are warranted. Adverse events appeared comparable or less frequent for UEMR compared with CEMR but still existed. Therefore, careful implementation of this new technique in clinical practice is important for its widespread use.

Efficacy of Underwater Endoscopic Mucosal Resection for Nonpedunculated Colorectal Polyps: A Systematic Review and Meta-Analysis

Recently, underwater endoscopic mucosal resection (UEMR) without submucosal injection was introduced as a new replacement for conventional EMR (CEMR) and was reported to be useful for resecting large colonic polyps. Here, we aimed to assess the efficacy and safety of these two methods by a systematic review and meta-analysis. We comprehensively searched multiple databases until July 2021 to identify randomized controlled trials (RCTs) comparing UEMR with CEMR. The primary outcomes were the proportion of R0 resection and mean procedure time, and the secondary outcomes were the proportion of en bloc resection and all adverse events. Three reviewers independently searched for articles, extracted data, and assessed the risk of bias. We evaluated the certainty of evidence using the Grading of Recommendations, Assessment, Development, and Evaluation approach. This study was registered in www.protocols.io (Protocol Integer ID: 40849). We included six RCTs (1,374 polyps). We judged that a meta-analysis was not available, and the data were summarized narratively for the proportion of R0 resection. Regarding procedure time, UEMR likely resulted in a large reduction (mean difference = -64.3 seconds; 95% confidence interval (CI) = -122.5 to -6.0 seconds; I2 = 86%; moderate certainty of evidence). UEMR likely resulted in a large increase in en bloc resection (odds ratio = 1.85; 95% CI = 1.15 to 2.98; I2 = 60%; moderate certainty of evidence). Percentages of adverse events were 0-17% with CEMR and 0-16% with UEMR. In summary, UEMR might have higher efficacy than CEMR in the endoscopic resection of nonpedunculated colorectal polyps, with likely a large reduction in procedure time.

Anchoring the snare tip is a feasible endoscopic mucosal resection method for small rectal neuroendocrine tumors

Small rectal neuroendocrine tumors (NETs) can be treated using cap-assisted endoscopic mucosal resection (EMR-C), which requires additional effort to apply a dedicated cap and snare. We aimed to evaluate the feasibility of a simpler modified endoscopic mucosal resection (EMR) technique, so-called anchored snare-tip EMR (ASEMR), for the treatment of small rectal NETs, comparing it with EMR-C. We retrospectively evaluated 45 ASEMR and 41 EMR-C procedures attempted on small suspected or established rectal NETs between July 2015 and May 2020. The mean (SD) lesion size was 5.4 (2.2) mm and 5.2 (1.7) mm in the ASEMR and EMR-C groups, respectively (p = 0.558). The en bloc resection rates of suspected or established rectal NETs were 95.6% (43/45) and 100%, respectively (p = 0.271). The rates of histologic complete resection of rectal NETs were 94.1% (32/34) and 88.2% (30/34), respectively (p = 0.673). The mean procedure time was significantly shorter in the ASEMR group than in the EMR-C group (3.12 [1.97] vs. 4.13 [1.59] min, p = 0.024). Delayed bleeding occurred in 6.7% (3/45) and 2.4% (1/41) of patients, respectively (p = 0.618). In conclusion, ASEMR was less time-consuming than EMR-C, and showed similar efficacy and safety profiles. ASEMR is a feasible treatment option for small rectal NETs.

Underwater vs conventional endoscopic mucosal resection in treatment of colorectal polyps: A meta-analysis

BACKGROUND

Underwater endoscopic mucosal resection (UEMR) of colorectal lesions is emerging as an alternative method to conventional endoscopic mucosal resection (EMR); however, it is still controversial whether there is a difference in the effectiveness between UEMR and EMR.

AIM

To evaluate the effectiveness and safety of UEMR in the treatment of colorectal polyps.

METHODS

Clinical studies comparing the effectiveness or safety of UEMR in the treatment of colorectal polyps were searched in medical databases, including PubMed, Embase, Cochrane Library, CNKI, and Wanfang Data, monographs, theses, and papers presented at conferences. Statistical analyses were performed using Revman 5.3 software.

RESULTS

Seven non-randomized controlled trials and one randomized controlled trial met the inclusion criteria. In total, 1382 patients (1511 polyps) were included in the study, including 722 who received UEMR and 789 who received EMR. In the UEMR and EMR groups, the en bloc resection rates were 85.87% and 73.89%, respectively, with a relative risk (RR) value of 1.14 (95% confidence interval [CI]: 1.01-1.30; P < 0.05). In the sub-group analysis, the en bloc resection rate showed no statistically significant difference between the EMR and UEMR groups for polyps less than 20 mm in diameter. However, a statistically significant difference was found between the EMR and UEMR groups for polyps equal to or greater than 20 mm in diameter. The post-endoscopic resection recurrence rates at 3-6 mo of the UEMR and EMR groups were 3.26% and 15.17%, respectively, with an RR value of 0.27 (95%CI: 0.09-0.83; P < 0.05). The post-endoscopic resection recurrence rates of UEMR and EMR at 12 mo were 6.25% and 14.40%, respectively, with an RR value of 0.43 (95%CI: 0.20-0.92; P < 0.05). Additionally, the incidence of adverse events was 8.17% and 6.21%, respectively, with an RR value of 1.07 (95%CI: 0.50-2.30; P > 0.05).

CONCLUSION

UEMR is an effective technique for colorectal polyps and appears to have some advantages over EMR, particularly with regard to some treatment outcomes.

Feasibility and safety of modified underwater endoscopic mucosal resection for colorectal polyps

BACKGROUND

Conventional endoscopic mucosal resection (EMR) with submucosal injection has been widely performed to remove colorectal polyps, although it often makes sessile lesions flattened and enlarged, resulting in the failure of lesion snaring. Air deflation and water immersion during underwater EMR (UEMR) sometimes interfere with the exposure of colorectal polyps. Modified UEMR may facilitate the resection of colorectal polyps due to integrating the advantages of EMR and UEMR.

AIM

To investigate the feasibility and safety of the modified UEMR in the treatment of colorectal polyps.

METHODS

Fifty-nine patients with 76 colorectal polyps treated by modified UEMR were enrolled in the study from July 2015 to June 2019, and compared with 43 patients with 65 colorectal polyps treated by UEMR during the same period. All lesions were classified as Paris Is or IIa, and the size of the polyp ranged from 1 cm to 3 cm in diameter. Endoscopic procedure was as follows: Once observed, the polyp was completely immersed by warm water infusion. The polyp was placed in the 6 o'clock direction. Following submucosal injection with normal saline plus methylene blue, an appropriate snare was used for en bloc resection. The mucosal defect was closed with clips. The excised specimen was sent for pathological evaluation after crystal violet staining.

RESULTS

All the 76 lesions in the study group were successfully resected by modified UEMR. Among them, 64 polyps less than 2 cm in size received en bloc resection. In 12 polyps ranging 2-3 cm in size, 5 received en bloc resection and 7 received piecemeal UEMR. The overall en bloc resection rate was 91%; the rate for those polyps < 2 cm was 100%, and the rate for polyps ranging from 2 cm to 3 cm was 42%. All the 65 lesions in the control group were successfully treated by conventional UEMR. Of 58 lesions less than 2 cm in size, 49 underwent en bloc resection and the other 9 underwent additional argon plasma coagulation (APC) due to residual lesion. Of 7 lesions ranging from 2 cm to 3 cm in size, 2 underwent en bloc resection, 1 undewent additional APC due to residual lesion, and the other 5 underwent piecemeal UEMR or were converted to modified endoscopic submucosal dissection. The overall en bloc resection rate in the control group was 76%; the rate for the lesions < 2 cm was 84%, and that for lesions 2-3 cm was 14%. During operation, minor bleeding occurred in 9 patients of the study group and 13 patients of the control group. There were no complications such as delayed bleeding and perforation in either group. During the follow-up period, local recurrence was found in 2 patients of the study group, and 9 patients of the control group.

CONCLUSION

Compared with conventional UEMR, modified UEMR can provide more excellent exposure for polyps, and achieve higher en bloc resection rate by discontinuous suction during tightening of the snare, resulting in a high complete resection rate and low recurrence rate.

Comparison of underwater endoscopic mucosal resection and endoscopic submucosal dissection of rectal neuroendocrine tumors (with videos)

BACKGROUND AND AIMS

The first choice of treatment for rectal neuroendocrine tumors (NETs) ≤10 mm in size is endoscopic resection. However, because rectal NETs usually invade the submucosal layer, achieving R0 resection is difficult. Endoscopic submucosal dissection (ESD) has a high R0 resection rate, and underwater endoscopic mucosal resection (UEMR) was recently introduced to ensure a negative resection margin easily and safely. The aim of this study was to evaluate the efficacy and safety of UEMR versus ESD for rectal NETs ≤10 mm in size.

METHODS

This retrospective observational study enrolled 115 patients with rectal NETs ≤10 mm in size who underwent ESD or UEMR between January 2015 and July 2019 at the National Cancer Center, Korea. The differences in R0 resection rate, adverse event rate, and procedure time between the ESD and UEMR groups were evaluated.

RESULTS

Of the 115 patients, 36 underwent UEMR and 79 underwent ESD. The R0 resection rate was not different between the UEMR and ESD groups (UEMR vs ESD, 86.1% vs 86.1%, P = .996). The procedure time was significantly shorter with UEMR (UEMR vs ESD, 5.8 ± 2.9 vs 26.6 ±13.4 minutes, P < .001). Two patients (2.5%, 2/79) experienced adverse events in the ESD group and but there were no adverse events in the UEMR group; however, this difference was not statistically significant.

CONCLUSION

UEMR is a safe and effective technique that should be considered when removing small rectal NETs. Further studies are warranted to define its role compared with ESD.

Comparison of underwater and conventional endoscopic mucosal resection for removing sessile colorectal polyps: a propensity-score matched cohort study

Background and study aims  Endoscopic mucosal resection (EMR) is a standard method for removing sessile colorectal polyps ≥ 10 mm. Recently, underwater EMR (UEMR) has been introduced as a potential alternative. However, the effectiveness and safety of UEMR compared with conventional EMR is un clear. Patients and methods  In this 1:1 propensity score (PS) matched retrospective cohort study, we compared the en bloc resection rates, procedure time, intraprocedural and delayed bleeding rates, and incidence of muscle layer injury. We also performed subgroup analyses by sizes of polyps (< 20 mm and ≥ 20 mm). Results  Among 350 polyps in 315 patients from August 2012 to November 2017, we identified 121 PS-matched pairs. Mean polyp size was 16.8 mm. With similar en bloc resection rates (EMR: 82.6 % vs. UEMR: 87.6 %, rate difference: 5.0, 95 % confidence interval [95 % CI]: - 4 to 13.9 %), UEMR demonstrated a shorter resection time (10.8 min vs. 8.6 min, difference: - 2.2 min, 95 % CI: - 4.1 to - 0.3 min) and a lower intraprocedural bleeding rate (15.7 % vs. 5.8 %, rate difference: - 9.9 %, 95 % CI: - 17.6 to - 2.2 %). Incidence of delayed bleeding and muscle layer injury were low in both groups. For polyps < 20 mm, effectiveness and safety outcomes were similar in both groups. For polyps ≥ 20 mm (42 PS-matched pairs), the UEMR group has a comparable en bloc resection rate with shorter procedure time and superior safety outcomes Conclusions  UEMR achieved an en bloc resection rate comparable to conventional EMR with less intraprocedural bleeding and a shorter procedure time.

Management of Gastrointestinal Neuroendocrine Tumors

Neuroendocrine neoplasms (NENs) are derived from neuroendocrine cell system and can have benign or malignant characteristics. They are rare tumors, but have been increasing in incidence over the past 40 years. Patients with NENs may develop symptoms due to primary tumor invasion, metastasis, or from secretion of hormonally active tumor substances. Multiple imaging modalities are used for diagnosis and staging, including specialty scans such as ¹¹¹In pentetreotide (Octreoscan) and ⁶⁸Gallium-DOTATATE, along with endoscopy, endoscopic ultrasound, and biochemical marker testing. Treatment involves both surgical approach, for both primary and metastatic lesions, as well as medical management for symptom management and disease progression. This article will review the current clinical knowledge regarding the diagnosis, treatment, and prognosis of these fascinating neoplasms and the associated hormonal syndromes.

Cost Analysis of Endoscopic Submucosal Dissection for the Treatment of Colorectal Lesions in China

Aim

The aim of the study was to evaluate costs associated with colonic endoscopic submucosal dissection (ESD) for treatment of colorectal cancer.

Methods

The study is a retrospective analysis of data on 395 patients treated by colonic ESD.

Results

The operation, consumable items, and medication accounted for 71% of the total costs for colonic ESD treatment. Medication and consumable items' costs were higher if lesions occurred in the transverse colon and right hemicolon compared to the left hemicolon. Medication, consumable items, and total costs were higher for larger lesions. Lesion numbers and carcinoma were associated with higher medication, consumable items, operation, and total costs. Positive surgical margins and complications of hemorrhage or perforation were positively correlated with higher costs for medication, consumable items, and total costs.

Conclusion

Labor costs for doctors and nurses remain low in China. Costs for medication and consumable items were higher for treatment involving the transverse colon or right hemicolon (vs. the left hemicolon), larger lesions, carcinoma, and a positive surgical margin. A benchmark cost estimate for ESD treatment including 4 days of postoperative hospitalization was determined to be approximately 5400 USD.