Successful outcomes of EMR-L with 3D-EUS for rectal carcinoids compared with historical controls

Current status of endoscopic resection for small rectal neuroendocrine tumors

Rectal neuroendocrine tumor (rNET) is an indolent malignancy often detected during colonoscopy screening. The incidence of rNET has increased approximately 10-fold over the past 30 years. Most rNETs detected during screening endoscopy are small, measuring < 10 mm. Current guidelines recommend endoscopic resection for small, well-differentiated rNET using modified endoscopic submucosal resection (mEMR) or endoscopic submucosal dissection. However, the optimal endoscopic treatment method remains uncertain. This paper summarizes the evidence on mEMR with submucosal stretching, mEMR without submucosal stretching, endoscopic submucosal dissection and endoscopic full-thickness resection. Given that rNETs often exhibit submucosal invasion, achieving adequate resection depth is crucial to ensure histological complete resection. mEMR with submucosal stretching appears favorable due to its high rate of histological complete resection, safety and convenience. Risk factors associated with lymph node and distant metastases are also discussed. A treatment algorithm is proposed to facilitate clinical decision-making.

Clinical outcomes of endoscopic resection for rectal neuroendocrine tumors: Advantages of endoscopic submucosal resection with a ligation device compared to conventional EMR and ESD

Objectives

Methods

Results

Conclusions

Resectability of Rectal Neuroendocrine Tumors Using Endoscopic Mucosal Resection with a Ligation Band Device and Endoscopic Submucosal Dissection

BACKGROUND

Rectal neuroendocrine tumors (NETs) < 10 mm in diameter, limited to the submucosa without local or distant metastasis, can be treated endoscopically. Endoscopic mucosal resection with a ligation band device (EMR-L) and endoscopic submucosal dissection (ESD) have been employed to resect rectal NETs. We evaluated and compared the clinical outcomes of EMR-L and ESD for endoscopic resection of rectal NETs G1 < 10 mm in diameter.

METHODS

We conducted a retrospective study of 82 rectal NETs in 82 patients who underwent either EMR-L or ESD. Therapeutic outcomes (en bloc resection and complete resection rates), procedure time, and procedure-related adverse events were evaluated. Additionally, we measured the distance of the lateral and vertical margins from the border of the tumor in pathologic specimens and compared the resectability between EMR-L and ESD.

RESULTS

Sixty-six lesions were treated using EMR-L and 16 using ESD. En bloc resection was achieved in all patients. The complete resection rate with EMR-L was significantly higher than that with ESD (95.5% vs.75.0%, p = 0.025). The prevalence of vertical margin involvement was significantly higher in the ESD group than in the EMR-L group (12.5% vs. 0%, p = 0.036), and ESD was more time consuming than EMR-L (24.21 ± 12.18 vs. 7.05 ± 4.53 min, p < 0.001). The lateral and vertical margins were more distant in the EMR-L group than in the ESD group (lateral margin distance, 1661 ± 849 vs. 1514 ± 948 μm; vertical margin distance, 277 ± 308 vs. 202 ± 171 μm).

CONCLUSIONS

EMR-L is more favorable for small rectal NETs with respect to therapeutic outcomes, procedure time, and technical difficulties. Additionally, EMR-L enables achievement of sufficient vertical margin distances.

Rectal Endoscopic Ultrasound in Clinical Practice

PURPOSE OF REVIEW

Endoscopic ultrasound (EUS) is routinely utilized for evaluation of disorders of the lower gastrointestinal tract. In this review, we summarize the current status of rectal EUS in clinical practice and describe recent developments in diagnostic and therapeutic rectal EUS.

RECENT FINDINGS

Recent guidelines recommend rectal EUS for rectal cancer staging as a second line modality in cases where MRI is contraindicated. Forward-viewing echoendoscopes and through the scope EUS miniprobes allow for EUS imaging of lesions through the entire colon and for evaluation beyond stenoses or luminal narrowings. EUS can be used to assess perianal disease and drain pelvic abscess associated with IBD, along with newer applications currently under investigation. For rectal varices, EUS can confirm the diagnosis, assess the optimal site for banding, guide therapy placement with sclerotherapy and/or coils, and assess response to treatment by confirming absence of flow. Therapeutic rectal EUS is emerging as a promising modality for drainage of pelvic fluid collection drainage and fiducial placement for rectal or prostatic cancer. Drug delivery mechanisms and substances that may increase the scope of therapy with rectal EUS are in varying stages of development. Rectal EUS continues to be an important modality for evaluation of benign and malignant disorders of the lower gastrointestinal tract, although its use as a cancer staging modality has declined due to improvements in MRI technology. Various technologies to enhance ultrasound imaging and for therapeutics have been developed that have or may contribute to expanded indications for rectal EUS.

[Endoscopic Treatment Outcome of Rectal Neuroendocrine Tumors Removed by Ligation-assisted Endoscopic Submucosal Resection]

BACKGROUND/AIMS

Ligation-assisted endoscopic submucosal resection (ESMR-L) is preferred for the treatment of rectal neuroendocrine tumors because its results are better than those for endoscopic mucosal resection (EMR), and the procedure time is shorter and the incidence of complications is lower than endoscopic submucosal dissection. The aim of this study was to evaluate the clinical usefulness of ESMR-L compared with EMR for rectal neuroendocrine tumors.

METHODS

From March 2007 to May 2017, 148 patients diagnosed with rectal neuroendocrine tumors were divided into ESMR-L and EMR groups and analyzed retrospectively.

RESULTS

Of 148 patients with rectal neuroendocrine tumor, 120 had ESMR-L and 28 had EMR. The ESMR-L group had a significantly higher rate of complete resection and curative resection than the EMR group (93.3% vs. 75.0% and 92.5% vs. 71.4%, p=0.009 and p=0.003, respectively).

CONCLUSIONS

ESMR-L for the treatment of small rectal neuroendocrine is a significantly superior modality to EMR.

Endoscopic mucosal resection with suction vs. endoscopic submucosal dissection for small rectal neuroendocrine tumors: a meta-analysis

OBJECTIVE

There are no guidelines or consensus on the optimal treatment measures for small rectal neuroendocrine tumors (NETs) at present. This meta-analysis was conducted to compare the efficacy and safety of endoscopic mucosal resection (EMR) with suction and endoscopic submucosal dissection (ESD) for the small rectal NETs.

METHODS

The literature searches were conducted using Pubmed and Embase databases, and then a meta-analysis was performed. The primary outcome was complete resection rate, and the secondary outcomes were complication rate, procedure time, and recurrence rate.

RESULTS

Fourteen studies with 823 patients were included in our meta-analysis. The overall complete resection rates in EMR with suction and ESD procedure were 93.65% (472/504) and 84.08% (243/289), respectively. The pooled analysis showed that EMR with suction could achieve a higher complete resection rate than ESD with significance (OR: 4.08, 95% CI: 2.42-6.88, p < .00001) when the outlier study was excluded, and procedure time was significantly shorter in the EMR with suction group than in the ESD group (SMD: -1.59, 95% CI: -2.27 to -0.90, p < .00001). Moreover, there was no significant difference in overall complication rate (OR: 0.56, 95% CI: 0.28-1.14, p = .11) and overall recurrence rate (OR: 0.76, 95% CI: 0.11-5.07, I²=48%) between EMR with suction and ESD group.

CONCLUSIONS

The present meta-analysis mostly based on retrospective studies show that EMR with suction is superior to ESD for small rectal NETs (≤10 mm) with higher complete resection rate, shorter procedure time, and similar overall complication rate and recurrence.

Hindgut neuroendocrine neoplasms - characteristics and prognosis

INTRODUCTION

The aim of the study was to analyze the clinicopathologic characteristics and prognostic factors of hindgut-rectal neuroendocrine neoplasms.

MATERIAL AND METHODS

The study included 38 patients with rectal neuroendocrine tumors who were treated at the Department of Endocrinology, Metabolism and Internal Diseases, Poznan University of Medical Sciences, Poznan, Poland from February 2010 to December 2015. The clinicopathological data were retrospectively reviewed, extracted, analyzed, and patients were followed up to determine their survival status. Follow-up data were available for all 38 patients. Uni- and multivariate Cox regression analyses were performed to determine the prognostic factors significantly associated with overall survival.

RESULTS

The tumors occurred mostly in the middle and lower rectum, and the most typical symptoms experienced by patients were hematochezia and diarrhea. The median distance between the tumors and the anal edges was 4.7 ±1.3 cm, and the median diameter of the tumors was 0.9 ±1.2 cm. The major pathological types were neuroendocrine neoplasm G1 in 31 patients, and neuroendocrine neoplasm G2 in 7 patients. Tumor-node-metastasis (TNM) stages I, II, III and IV tumors accounted for 76.3% (29/38), 5.3% (2/38), 7.9% (3/38) and 10.5% (4/38) of patients, respectively. The main treatment method was transanal extended excision or endoscopic resection. The 1-, 3- and 5-year survival rates of the whole group of patients were 100%, 83.7%, and 75.3%, respectively.

CONCLUSIONS

Univariate analysis showed that age (p = 0.022), tumor diameter (p < 0.001), histological type (p < 0.001), and TNM stage (p < 0.001) were all prognostic factors.

Endoscopic treatments for rectal neuroendocrine tumors smaller than 16 mm: a meta-analysis

OBJECTIVE

Endoscopic mucosal resection (EMR), including conventional EMR (c-EMR) and modified EMR (m-EMR), was applied to remove small rectal neuroendocrine tumors (NETs). We aim to evaluate treatment outcomes of endoscopic submucosal dissection (ESD), m-EMR and c-EMR for rectal NETs <16 mm.

METHODS

The PubMed, Cochrane Library and Elsevier Science Direct were searched to identify eligible articles. After quality assessment and data extraction, meta-analysis was performed. The main outcomes were complete resection rate, overall complication rate, procedure time and local recurrence rate.

RESULTS

Compared with c-EMR, ESD could achieve higher complete resection rate (OR = 4.38, 95%CI: 2.43-7.91, p < 0.00001) without increasing overall complication rates (OR = 2.21, 95%CI: 0.56-8.70, p = 0.25). However, ESD was more time-consuming than c-EMR (MD = 6.72, 95%CI: 5.84-7.60, p < 0.00001). Compared with m-EMR, ESD did not differ from m-EMR in complete resection and overall complication rates (OR = 0.80, 95%CI: 0.51-1.27, p = 0.34; OR = 1.91, 95%CI: 0.75-4.86, p = 0.18, respectively). However, ESD was more time-consuming than m-EMR (MD = 12.21, 95%CI: 7.78-16.64, p < 0.00001). Compared with c-EMR, m-EMR could achieve higher complete resection rate (OR = 4.23, 95%CI: 2.39-7.50, p < 0.00001) without increasing overall complication rate (OR = 1.07, 95%CI: 0.35-3.32, p = 0.90). Moreover, m-EMR was not time-consuming than c-EMR (MD = 2.01, 95%CI: -0.37-4.40, p= 0.10). The local recurrence rate was 0.84% (9/1067) during follow-up.

CONCLUSIONS

Both ESD and m-EMR have great advantages over c-EMR in complete resection rate without increasing safety concern while m-EMR shares similar outcomes with ESD for rectal NETs <16 mm. The results should be confirmed by well-designed, multicenter, randomized controlled trials with large samples and long-term follow-ups from more countries.

Survival trial design and monitoring using historical controls

In this paper, we propose a multistage group sequential procedure to design survival trials using historical controls. The formula for the number of events required for historical control trial designs is derived. Furthermore, a transformed information time is proposed for trial monitoring. An example is given to illustrate the application of the proposed methods to survival trial designs using historical controls. Copyright © 2016 John Wiley & Sons, Ltd.

Advances in endoscopic ultrasound imaging of colorectal diseases

The development of endoscopic ultrasound (EUS) has had a significant impact for patients with digestive diseases, enabling enhanced diagnostic and therapeutic procedures, with most of the available evidence focusing on upper gastrointestinal (GI) and pancreatico-biliary diseases. For the lower GI tract the main application of EUS has been in staging rectal cancer, as a complementary technique to other cross-sectional imaging methods. EUS can provide highly accurate in-depth assessments of tumour infiltration, performing best in the diagnosis of early rectal tumours. In the light of recent developments other EUS applications for colorectal diseases have been also envisaged and are currently under investigation, including beyond-rectum tumour staging by means of the newly developed forward-viewing radial array echoendoscope. Due to its high resolution, EUS might be also regarded as an ideal method for the evaluation of subepithelial lesions. Their differential diagnosis is possible by imaging the originating wall layer and the associated echostructure, and cytological and histological confirmation can be obtained through EUS-guided fine needle aspiration or trucut biopsy. However, reports on the use of EUS in colorectal subepithelial lesions are currently limited. EUS allows detailed examination of perirectal and perianal complications in Crohn’s disease and, as a safe and less expensive investigation, can be used to monitor therapeutic response of fistulae, which seems to improve outcomes and reduce the need for additional surgery. Furthermore, EUS image enhancement techniques, such as the use of contrast agents or elastography, have recently been evaluated for colorectal indications as well. Possible applications of contrast enhancement include the assessment of tumour angiogenesis in colorectal cancer, the monitoring of disease activity in inflammatory bowel disease based on quantification of bowel wall vascularization, and differentiating between benign and malignant subepithelial tumours. Recent reports suggest that EUS elastography enables highly accurate discrimination of colorectal adenocarcinomas from adenomas, while inflammatory bowel disease phenotypes can be distinguished based on the strain ratio calculation. Among EUS-guided therapies, the drainage of abdominal and pelvic collections has been regarded as a safe and effective procedure to be used as an alternative for the transcutaneous route, while the placing of fiducial markers under EUS guidance for targeted radiotherapy in rectal cancer or the use of contrast microbubbles as drug-delivery vehicles represent experimental therapeutic applications that could greatly impact the forthcoming management of patients with colorectal diseases, pending on further investigations.

Comparing endoscopic mucosal resection with endoscopic submucosal dissection: the different endoscopic techniques for colorectal tumors

BACKGROUND

Endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) are used for the removal of colorectal tumors. There are no current guidelines or consensus on the optimal treatment strategy for these lesions. A meta-analysis was conducted to compare the effectiveness and safety of ESD and EMR for colorectal tumors.

METHODS

For the years 1966 until October 2014, Medline, PubMed, Scopus, Web of Science, and Cochrane Central Register of Controlled Trials were searched for articles comparing the effectiveness and safety of ESD and EMR. STATA 11.0 and RevMan 5.0 were used for meta-analysis and publication bias.

RESULTS

Seventeen articles were included in this meta-analysis. ESD was more effective than EMR in endoscopic complete resection rate (odds ratio [OR] = 2.81; 95% confidence interval [CI], 1.39-5.70; Z = 2.86; P = 0.004) and pathologic complete resection rate (OR = 2.81; 95% CI, 1.39-5.70; Z = 2.86; P = 0.004). ESD resulted in a higher perforation rate (OR = 5.27; 95% CI, 2.75-10.08; Z = 5.01; P < 0.00001) and a lower recurrence rate (OR = 0.14; 95% CI, 0.06-0.30; Z = 5.04; P < 0.00001). The tumor size was larger in the ESD group (OR = 3.09; 95% CI, 1.54-4.63; Z = 3.92; P < 0.0001), and the procedure time was longer in the ESD group (OR = 21.39; 95% CI, 10.33-32.46; Z = 3.79; P = 0.0002). But bleeding rate did not differ significantly (OR = 1.34; 95% CI, 0.81-2.20; Z = 1.14; P = 0.25). There was no publication bias analyzed by Begg test and Egger test.

CONCLUSIONS

The study indicates that ESD is the better treatment for colorectal tumors for its higher complete resection rate despite the longer procedure time and higher perforation rate.

Advantage of endoscopic mucosal resection with a cap for rectal neuroendocrine tumors

AIM: To compare the outcomes of endoscopic mucosal resection with a cap (EMR-C) with those of endoscopic submucosal dissection (ESD) for the resection of rectal neuroendocrine tumors.

METHODS: One hundred and sixteen lesions in 114 patients with rectal neuroendocrine tumor (NET) resected with EMR-C or ESD were included in the study. This study was performed at Pusan National University Yangsan Hospital between July 2009 and August 2014. We analyzed endoscopic complete resection rate, pathologic complete resection rate, procedure time, and adverse events in the EMR-C (n = 65) and ESD (n = 51) groups. We also performed a subgroup analysis by tumor size.

RESULTS: Mean tumor size was 4.62 ± 1.66 mm in the EMR-C group and 7.73 ± 3.14 mm in the ESD group (P < 0.001). Endoscopic complete resection rate was 100% in both groups. Histologic complete resection rate was significantly greater in the EMR-C group (92.3%) than in the ESD group (78.4%) (P = 0.042). Mean procedure time was significantly longer in the ESD group (14.43 ± 7.26 min) than in the EMR-C group (3.83 ± 1.17 min) (P < 0.001). Rates of histologic complete resection without complication were similar for tumor diameter ≤ 5 mm (EMR-C, 96%; ESD, 100%, P = 0.472) as well as in cases of 5 mm < tumor diameter ≤ 10 mm (EMR-C, 80%; ESD, 71.0%, P = 0.524).

CONCLUSION: EMR-C may be simple, faster, and more effective than ESD in removing rectal NETs and may be preferable for resection of small rectal NETs.

Tips and tricks for better endoscopic treatment of colorectal tumors: usefulness of cap and band in colorectal endoscopic mucosal resection

Endoscopic mucosal resection (EMR) is an endoscopic alternative to surgical resection of mucosal and submucosal neoplastic lesions. Prior to the development of knives, EMR could be performed with accessories to elevate the lesion. After the development of various knives, en bloc resection was possible without other accessories. So, recently, simple snaring without suction or endoscopic submucosal dissection using knife in the epithelial lesions such as adenoma or early mucosal cancer has been performed. However, for easy and complete resection of subepithelial lesions such as carcinoid tumor, a few accessories are needed. Complete resection of rectal carcinoid tumors is difficult to achieve with conventional endoscopic resection techniques because these tumors often extend into the submucosa. The rate of positive resection margin for tumor is lower in the group of EMR using a cap (EMR-C) or EMR with a ligation device (EMR-L) than conventional EMR group. EMR-C and EMR-L (or endoscopic submucosal resection with a ligation device) may be a superior method to conventional EMR for removing small rectal carcinoid tumors.

Endoscopic resection for gastrointestinal neuroendocrine tumors

Gastrointestinal (GI) and neuroendocrine tumors (NETs) can be treated by mini-invasive endoscopic resection when localized in the superficial layers of the bowel wall and their size is <20 mm. Endoscopic diagnosis of NETs is usually incidental or suspected after clinical, laboratory or imaging findings. Endoscopic mucosal resection is the most commonly used technique for NET removal, endoscopic submucosal dissection is indicated in selected cases, while papillectomy is feasible for ampullary lesions. Histopathologic assessment of the resection margin (circumferential and deep) is important for staging. Incidence of endoscopic mucosal resection-/endoscopic submucosal dissection-related complications for removal of GI NETs are similar to those reported for other GI lesions. Endoscopic follow-up is based on histopathologic characteristics of the resected NETs and its site. NETs >20 mm in size, with penetration of the muscle layer and/or serosa are at high risk for metastases and surgical approach is recommended when feasible.

Treatment outcomes according to endoscopic treatment modalities for rectal carcinoid tumors

BACKGROUND

Despite a growing understanding of the clinical effectiveness of endoscopic treatment for small rectal carcinoid tumors, there is still controversy concerning the best endoscopic treatment for resecting rectal carcinoid tumors easily and effectively.

OBJECTIVES

The objective of the present study was to compare the therapeutic efficacy and safety of endoscopic submucosal resection with a ligation device (ESMR-L) with endoscopic submucosal dissection (ESD) for rectal carcinoid tumors. In addition, a conventional snare-based endoscopic mucosal resection (EMR) was included in the study and compared with both ESMR-L and ESD.

METHODS

A retrospective analysis was performed in 115 patients who underwent endoscopic resection of a rectal carcinoid tumor between January 2005 and June 2011. These patients were classified into three groups according to the type of endoscopic procedure: EMR group (n=33), ESMR-L group (n=40) and ESD group (n=44).

RESULTS

The complete resection rate of the EMR group was significantly lower than those of the ESMR-L and ESD groups (77.4 vs. 100 and 97.7%, P=0.002 and P=0.007). Tumor-free vertical margins were significantly greater in the ESMR-L and ESD groups than in the EMR group (ESMR-L and ESD vs. EMR group, P=0.013 and P=0.041). The curative resection rate of rectal carcinoid tumors in the EMR group was 77.4%, which was significantly lower than that of the ESMR-L (95%, 38/40) and EDS groups (97.7%, 43/44) (77.4% vs. 95%, P=0.036 and 77.4% vs. 97.7%, P=0.007).

CONCLUSIONS

Our results show that ESMR-L and ESD might be superior to conventional EMR for the treatment of small rectal carcinoid tumors.

Comparison of endoscopic resection therapies for rectal carcinoid tumor: endoscopic submucosal dissection versus endoscopic mucosal resection using band ligation

BACKGROUND

Endoscopic mucosal resection (EMR) has been the endoscopic treatment of choice for rectal carcinoid tumors <10 mm in size. Endoscopic submucosal dissection (ESD) may cause more severe complications, longer operation time, and higher cost than EMR.

AIM

: To compare EMR using band ligation (EMR-B) method with ESD for the endoscopic treatment of rectal carcinoid tumors.

METHODS

From November 2008 to September 2011, we enrolled consecutive patients with rectal carcinoid tumors <10 mm in diameter and without lymph node enlargement. Rate of complete resection rate, incidence of complications, and length of procedures were evaluated.

RESULTS

Sixty patients were enrolled (31 ESD cases and 29 EMR-B cases). The mean age was 48.03±13.09 years. Both groups had similar mean tumor diameter (EMR-B 4.34±1.75 vs. ESD 5.22±2.09 mm; P=0.084). Resection time was longer in the ESD group than in the EMR-B group (15.09±5.73 vs. 6.37±5.52 min; P<0.001). The complete resection rate was 80.6% (25 of 31) in the ESD group and 82.8% (24 of 29) in the EMR-B group (P=0.833). In incomplete resection cases, neither local recurrence nor distant metastasis was detected during the follow-up period.

CONCLUSIONS

Compared with ESD, EMR-B resulted in a comparable histologically complete resection rate and took less time to perform. Given the advantages of easier and shorter procedure time, EMR-B may be considered the treatment of choice for small rectal carcinoid tumors.

Endoscopic mucosal resection vs endoscopic submucosal dissection for rectal carcinoid tumours: a systematic review and meta-analysis

AIM

Endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) are used for the removal of rectal carcinoid tumours. There are no current guidelines or consensus on the optimal treatment strategy for these lesions. A systematic review was conducted to compare the efficacy and safety of ESD and EMR.

METHOD

The generation of inclusion criteria and analysis of data were based on Preferred Reporting Items for Systematic Reviews and Meta-Analyses recommendations. A systematic literature review was conducted using the following databases: Medline, Embase, SpringerLink, Elsevier ScienceDirect, Science Citation Index and the Cochrane Library. Only papers comparing treatment of rectal carcinoid tumours by EMR and by ESD were selected. The data collected included the patients' demographic information, interventions made, observed outcome and sources of bias.

RESULTS

Four papers were included in this systematic review and meta-analysis. ESD was more effective than EMR in complete resection (OR 0.29; 95% CI 0.14-0.58; P = 0.000). ESD was as safe as EMR [rate difference (RD) -0.01; 95% CI -0.07 to 0.05; P = 0.675]. Recurrence rates did not differ significantly between the EMR and ESD groups (RD 0.04; 95% CI -0.01 to 0.09; P = 0.150). The duration of ESD was longer than EMR (standardized mean difference -1.73; 95% CI -2.73 to -0.74; P = 0.001).

CONCLUSION

The study indicates that ESD is the better treatment for rectal carcinoid tumours.

Long-term prognosis of an endoscopically treated rectal neuroendocrine tumor: 10-year experience in a single institution

BACKGROUND AND AIM

The endoscopic techniques for treating a small rectal neuroendocrine tumor (NET) are performed in most large centers; however, the endoscopic management of this condition is not well established. This study was designed to determine the long-term prognosis of endoscopically resected NET.

METHODS

We prospectively studied patients with endoscopically treated rectal NET in Seoul St Mary's hospital, between January 2000 and June 2010. The long-term outcomes were analyzed in association with the pathological complete resection and resection procedures.

RESULTS

Seventy-seven patients (48 men and 29 women; mean age, 52.3 years; range, 23-77 years) were included. The average NET size was 7.0±2.8 mm (range, 3-16 mm). There was no procedure-related complication. En-bloc removal was achieved for all lesions, and the rate of histological complete resection was 75.3% (58/77). Histological complete resection rates were 71.4% (10/14) by conventional endoscopic mucosal resection (EMR), 74.1% (43/58) by a two-channel EMR, and 100.0% (5/5) by endoscopic submucosal dissection (ESD). Among six patients with incomplete histological resection, two underwent additional EMR, two underwent transanal endoscopic microsurgery, and two underwent low anterior section with lymph node dissection. The remaining 13 patients with 'possible' remnant NET underwent regular endoscopic surveillance without additional resection. In the latter group, only one patient had local recurrence, detected on regular colonoscopic surveillance, after 56 months and was treated with additional EMR. All of the patients are alive and 98.7% (76/77) of the patients are free from disease during the follow-up periods.

CONCLUSION

Endoscopic resection is a safe and effective modality and may potentially be used for the treatment of NETs smaller than 15 mm in diameter, those confined to the submucosal layer, and those without metastasis. Local treatment was believed to be curative in cases with complete histological resection. In addition, this treatment may have an excellent prognosis in patients with 'possible' remnant NET.

Calculating sample size in trials using historical controls

BACKGROUND

Makuch and Simon [Sample size considerations for non-randomised comparative studies. J Chronic Dis 1980; 33: 175-81.] developed a sample size formula for historical control trials. When assessing power, they assumed the true control treatment effect to be equal to the observed effect from the historical control group. Many researchers have pointed out that the Makuch-Simon approach does not preserve the nominal power and type I error when considering the uncertainty in the true historical control treatment effect.

PURPOSE

To develop a sample size formula that properly accounts for the underlying randomness in the observations from the historical control group.

METHODS

We reveal the extremely skewed nature in the distributions of power and type I error, obtained over all the random realizations of the historical control data. The skewness motivates us to derive a sample size formula that controls the percentiles, instead of the means, of the power and type I error.

RESULTS

A closed-form sample size formula is developed to control arbitrary percentiles of power and type I error for historical control trials. A simulation study further demonstrates that this approach preserves the operational characteristics in a more realistic scenario where the population variances are unknown and replaced by sample variances.

LIMITATIONS

The closed-form sample size formula is derived for continuous outcomes. The formula is more complicated for binary or survival time outcomes.

CONCLUSIONS

We have derived a closed-form sample size formula that controls the percentiles instead of means of power and type I error in historical control trials, which have extremely skewed distributions over all the possible realizations of historical control data.

Endoscopic treatment of rectal carcinoid tumors

BACKGROUND

Various methods have been reported for the endoscopic treatment of rectal carcinoid tumors. The present study was designed to identify the optimal treatment strategy for an endoscopic resection.

METHODS

Forty rectal carcinoid tumors of 38 patients were treated endoscopically. The indication criteria, complete resection rate, selection of treatment, local recurrence, distant metastases, and complications were analyzed. All tumors were estimated to measure 1 cm or less in diameter, without muscular invasion, atypical features, and lymph node metastases to the pararectal region.

RESULTS

Complete resection of the lesions was obtained in 75.0% (30/40). The complete resection rates were 20.0% (1/5) by conventional polypectomy, 84.6% (22/26) by a two-channel endoscopic mucosal resection, and 77.8% (7/9) by endoscopic submucosal dissection. The 10 cases that did not show a clear submucosal layer after initial endoscopic treatment received additional endoscopic microwave coagulation therapy. There were no local or distant recurrences in the followed-up periods (median, 6.4 years). No difference was observed in the complete resection rate between two-channel endoscopic mucosal resection and endoscopic submucosal dissection.

CONCLUSIONS

Small carcinoid tumors measuring less than 1 cm in diameter can therefore be managed endoscopically with no recurrence or spread. The selection of endoscopic treatment should be made after taking such factors as cost-effectiveness, expertise, and experience into careful consideration.

Endoscopic submucosal dissection of a rectal carcinoid tumor using grasping type scissors forceps

Endoscopic submucosal dissection (ESD) with a knife is a technically demanding procedure associated with a high complication rate. The shortcomings of this method are the inability to fix the knife to the target lesion, and compression of the lesion. These can lead to major complications such as perforation and bleeding. To reduce the risk of complications related to ESD, we developed a new grasping type scissors forceps (GSF), which can grasp and incise the targeted tissue using electrosurgical current. Colonoscopy on a 55-year-old woman revealed a 10-mm rectal submucosal nodule. The histological diagnosis of the specimen obtained by biopsy was carcinoid tumor. Endoscopic ultrasonography demonstrated a hypoechoic solid tumor limited to the submucosa without lymph node involvement. It was safely and accurately resected without unexpected incision by ESD using a GSF. No delayed hemorrhage or perforation occurred. Histological examination confirmed the carcinoid tumor was completely excised with negative resection margin.