Endoscopic resection for rectal carcinoid tumors: comparison of polypectomy and endoscopic submucosal resection with band ligation

Short-term outcomes of endoscopic resection for colorectal neuroendocrine tumors: Japanese multicenter prospective C-NET STUDY

OBJECTIVES

The incidence of colorectal neuroendocrine tumors (NETs) has increased with colorectal cancer screening programs and increased colonoscopies. The management of colorectal NETs has recently shifted from radical surgery to endoscopic resection. We aimed to evaluate the short-term outcomes of various methods of endoscopic resection for colorectal NETs.

METHODS

Among those registered in the C-NET STUDY, patients with colorectal NETs who underwent endoscopic treatment as the initial therapy were included. Short-term outcomes, such as the en bloc resection rate and R0 resection (en bloc resection with tumor-free margin) rate, were analyzed based on treatment modalities.

RESULTS

A total of 472 patients with 477 colorectal NETs received endoscopic treatment. Of these, 418 patients with 421 lesions who met the eligibility criteria were included in the analysis. The median age of the patients was 55 years, and 56.9% of them were men. The lower rectum was the most commonly affected site (88.6%), and lesions <10 mm accounted for 87% of the cases. Endoscopic submucosal resection with a ligation device (ESMR-L, 56.5%) was the most common method, followed by endoscopic submucosal dissection (ESD, 31.4%) and endoscopic mucosal resection using a cap (EMR-C, 8.5%). R0 resection rates <10 mm were 95.5%, 94.8%, and 94.3% for ESMR-L, ESD, and EMR-C, respectively. All 16 (3.8%) patients who developed treatment-related complications could be treated conservatively. Overall, 23 (5.5%) patients had incomplete resection without independent clinicopathological risk factors.

CONCLUSION

ESMR-L, ESD, and EMR-C were equally effective and safe for colorectal NETs with a diameter <10 mm.

Recurrence pattern and surveillance strategy for rectal neuroendocrine tumors after endoscopic resection

BACKGROUND AND AIM

Endoscopic resection is highly effective treatment option for rectal neuroendocrine tumors (NETs) as they usually present as small localized tumors. However, there are no well-established surveillance strategies following endoscopic resection. We established our own protocol for the surveillance of rectal NETs after endoscopic resection since 2013. This study aimed to assess the outcome and to optimize the surveillance strategies after endoscopic resection.

METHODS

We retrospectively analyzed the data of patients with endoscopically treated rectal NETs between January 2013 and April 2018 at Samsung Medical Center. We analyzed 337 patients with a median follow-up duration of 35.0 months (min-max: 12.0-88.3).

RESULTS

A total of 329 (97.6%) patients had tumors ≤ 1 cm in size, and eight (2.4%) patients had tumors > 1 cm in diameter. Synchronous rectal NETs were diagnosed in nine (2.7%) patients. Thirteen (3.9%) patients were identified as having positive resection margins. Regardless of the salvage treatment, none of these patients developed recurrence. Metachronous rectal NETs were diagnosed in nine (2.7%) patients. Metachronous lesions were associated with the number of synchronous lesions at initial diagnosis (P < 0.001, hazard ratio = 1.75, 95% confidence interval = 1.38-2.23). Extracolonic metastasis was not detected in this study.

CONCLUSION

Although initial screening for detecting metastatic lesions using computed tomography is recommended, repeated imaging for detecting extracolonic recurrence was not necessary for small non-metastatic rectal NETs. However, regular endoscopic follow-up seems reasonable, especially in case of synchronous rectal NETs, for detecting metachronous rectal NETs.

Comparison of conventional and modified endoscopic mucosal resection methods for the treatment of rectal neuroendocrine tumors

BACKGROUND/AIM

Small rectal neuroendocrine tumors (NETs) confined to the submucosa are endoscopically resectable. Because most rectal NETs are submucosal tumors, conventional endoscopic mucosal resection (cEMR) may not result in a complete resection. This study investigated whether modified EMRs, namely endoscopic submucosal resection with ligation (ESMR-L), EMR with precutting (EMR-P), and strip biopsy are superior to cEMR for achieving histologically complete resection (HCR) of rectal NETs.

METHODS

Medical records of 215 patients who were treated with endoscopic resections for rectal NETs between January 2011 and July 2019 were retrospectively enrolled. Of the patients, 110, 33, 29, and 43 underwent cEMR, ESMR-L, EMR-P, and strip biopsy, respectively. For each method, HCR and en bloc resection rates, procedure times, and complication rates were measured.

RESULTS

HCR was achieved with cEMR, EMR-P, ESMR-L, and strip biopsies for 74.5%, 90.9%, 93.1%, and 90.7% of cases, respectively. The HCR rate for cEMR was inferior to those of the modified EMRs (p = 0.045 for cEMR vs. EMR-P; p = 0.031 for cEMR vs. ESMR-L; p = 0.027 for cEMR vs. strip biopsy). Among the three modified EMRs, there was no significant difference in achieving HCR (p = 1.000). En bloc resection (p = 0.096) and complication rates (p = 0.071) were not significantly different among the four EMR methods, although EMR-P required the longest procedure time (p = 0.000).

CONCLUSIONS

All three modified EMRs are superior to cEMR and are equally effective for achieving HCR of rectal NETs.

Comparison between cap-assisted and ligation-assisted endoscopic mucosal resection for rectal neuroendocrine tumors

Background:

Modified endoscopic mucosal resection (EMR) is considered a treatment option for rectal neuroendocrine tumors (NETs) <10 mm in diameter. In this study, we evaluated the clinical outcomes of cap-assisted EMR (EMR-C) and EMR with a ligating device (EMR-L).

Methods:

We retrospectively analyzed 158 patients with 162 rectal NETs treated endoscopically at a single Korean tertiary hospital between March 2010 and November 2017. We evaluated the rates of endoscopic en bloc resection, histologic complete resection, and procedural complications according to the treatment method.

Results:

Among 162 rectal NETs, 42 were treated with EMR-C and 120 with EMR-L. The endoscopic en bloc resection rate was higher in the EMR-L group than in the EMR-C group (100% vs. 92.9%, P=0.003). A trend was observed towards a superior histologic complete resection rate in the EMR-L group, but it was not statistically significant (92.5% vs. 83.3%, P=0.087). There were no significant differences in procedural complications (P=0.870). In a multivariate analysis, a tumor located ≥10 cm from the anal verge was related to histologic incomplete resection (P=0.039).

Conclusion:

EMR-L may be the preferable treatment method, considering both endoscopic en bloc resection rate and histologic complete resection rate.

Endoscopic, transanal, laparoscopic, and transabdominal management of rectal neuroendocrine tumors

Rectal neuroendocrine tumors (RNET) are rare tumors but their prevalence is constantly increasing due to a prolonged survival and rising incidence related to a growing number of colonoscopies and improved knowledge. Their main prognostic determinant is tumor stage. While most RNET are localized, their management should be tailored depending on the presence or absence of the factors predictive of lymph-node metastases including tumor size, endoscopic aspect, T stage, grade and lymphovascular invasion. Endoscopic ultrasonography is the most relevant technique for locoregional assessment. Low-risk RNET can be treated using advanced endoscopic resection techniques or transanal endoscopic microsurgery, in expert centers because they require technicity and experience. Conversely, radical surgery with lymphadenectomy should be proposed in the presence of any pejorative factor. The long-term evolution of RNET remains to be specified, and prospective studies should be conducted in order to determine the relevance of the current management strategies.

Colorectal Neuroendocrine Neoplasms: Areas of Unmet Need

The subject of colorectal neuroendocrine neoplasms (NENs), subdivided into well-differentiated NENs, termed neuroendocrine tumours (NETs; grade (G) 1 and 2), and poorly differentiated NENs, termed neuroendocrine carcinomas (NECs; G3) according to the 2010 World Health Organisation (WHO) classification, has arguably not had as much attention or study as NENs occurring in other sites. Colorectal NETs and NECs are however easier to study than many others since they are usually not difficult to remove and are increasingly detected because of intensified colorectal cancer screening and surveillance programmes. Colorectal NETs and NECs show site-specific heterogeneity with variable behaviour and different therapeutic options; these various aspects provide unique challenges. Because of bowel cancer screening programmes, colorectal NENs, like conventional adenocarcinomas, may be diagnosed at a stage that is associated with improved survival. In this article we intend to describe and define areas of unmet needs relating to the epidemiology, classification, pathology, diagnosis and therapy of colorectal NETs (including NETs G3), colorectal NECs, and finally, mixed adeno-neuroendocrine carcinomas (MANECs) by reviewing and discussing the relevant literature.

Endoscopic submucosal dissection for small submucosal tumors of the rectum compared with endoscopic submucosal resection with a ligation device

AIM

To evaluate the efficacy and safety of endoscopic submucosal dissection (ESD) for small rectal submucosal tumors (SMTs).

METHODS

Between August 2008 and March 2016, 39 patients were treated with endoscopic submucosal resection with a ligation device (ESMR-L) (n = 21) or ESD (n = 18) for small rectal SMTs in this study. Twenty-five lesions were confirmed by histological evaluation of endoscopic biopsy prior to the procedure, and 14 lesions were not evaluated by endoscopic biopsy. The results for the ESMR-L group and the ESD group were retrospectively compared, including baseline characteristics and therapeutic outcomes.

RESULTS

The rate of en bloc resection was 100% in both groups. Although the rate of complete endoscopic resection was higher in the ESD group than in the ESMR-L group (100% vs 95.2%), there were no significant differences between the two groups (P = 0.462). In one patient in the ESMR-L group with a previously biopsied tumor, histological complete resection with a vertical margin involvement of carcinoid tumor could not be achieved, whereas there was no incomplete resection in the ESD group. The mean length of the procedure was significantly greater in the ESD group than in the ESMR-L group (14.7 ± 6.4 min vs 5.4 ± 1.7 min, P < 0.05). The mean period of the hospitalization was also significantly longer in the ESD group than in the ESMR-L group (3.7 ± 0.9 d vs 2.8 ± 1.5 d, P < 0.05). Postoperative bleeding was occurred in one patient in the ESMR-L group.

CONCLUSION

Both ESMR-L and ESD were effective for treatment of small rectal SMTs. ESMR-L was simpler to perform than ESD and took less time.

Long-Term Clinical Outcomes of Rectal Neuroendocrine Tumors According to the Pathologic Status After Initial Endoscopic Resection: A KASID Multicenter Study

OBJECTIVES

With advances in diagnostic endoscopy, the detection of rectal neuroendocrine tumors (NETs) has increased. However, clinical outcomes, especially after endoscopic treatment, are still unclear. The aim of this study was to determine the long-term clinical outcomes of endoscopically resected rectal NETs according to the pathologic status after initial resection.

METHODS

In this large, multicenter, retrospective cohort study, we analyzed the medical records of patients who underwent endoscopic resection of rectal NETs and were followed for ≥24 months at 16 university hospitals. The outcomes of interest were local or distant recurrence and metachronous lesions.

RESULTS

On the pathologic assessment of 407 patients, the resection margin status was positive in 76 (18.7%) and indeterminate in 72 (17.7%) patients. Patients whose rectal NETs were diagnosed or suspected as NETs before resection showed a much higher complete resection rate than those whose tumors were resected as polyps and then diagnosed (P<0.001). Fourteen patients received salvage treatment at 1.9±2.8 months after initial treatment. During a median follow-up period of 45.0 months, local recurrence occurred in 3 (0.74%) patients, but there was no recurrence in the lymph nodes or distant organs. Metachronous rectal NETs were diagnosed in 3 (0.74%) patients. According to the pathologic status after initial resection, local recurrence and metachronous lesions occurred in 1 (0.4%) and 2 (0.8%) patients, respectively, in the pathologic tumor-free group, whereas they occurred in 2 (1.4%) and 1 (0.7%) patients, respectively, in the indeterminate group.

CONCLUSIONS

Considering the long-term prognosis including that for recurrences or metachronous lesions, endoscopic resection is an efficient and a safe modality for the treatment of rectal NETs. This treatment may result in favorable clinical outcomes in patients with tumors of indeterminate pathology, as well as in pathologic tumor-free cases after initial resection.

Dilemmas in Endoscopic Management of Rectal Neuroendocrine Tumors: A Case-Based Discussion

Rectal neuroendocrine tumors are uncommon neoplasms that historically were regarded as having an indolent course. Due to the widespread use of screening colonoscopy neuroendocrine tumors of the rectum are identified with increasing frequency. More recent literature has suggested that rectal neuroendocrine tumors may progress in a more malignant fashion than previously believed. In this case-based discussion we present management dilemmas, analyze current guidelines, and highlight the role of endoscopic ultrasound, endoscopic resection, and surgery.

A tailored approach for endoscopic treatment of small rectal neuroendocrine tumor

INTRODUCTION

Resection of rectal neuroendocrine tumors (NETs) less than 1 cm in diameter can be performed using various endoscopic techniques. Endoscopic mucosal resection (EMR) traditionally had suboptimal complete resection rate compared to endoscopic submucosal resection with band ligation (ESMR-L). However, the previous studies did not consider the characteristics of rectal NETs. The aim of our study is to compare the efficacy of ESMR-L and EMR using tailored approach according to the characteristics of rectal NETs.

METHODS

82 rectal NETs in 77 patients treated by ESMR-L (n = 48) or EMR (n = 34) between September 2007 and October 2012 were retrospectively analyzed. ESMR-L was used for flat-type tumors or tumors with non-lifting sign after submucosal injection. Conventional EMR was used for elevated-type tumors or tumors with well-lifting sign after submucosal injection.

RESULTS

The pathological complete resection rate was higher in the ESMR-L group (45 lesions, 93.8%) compared with the EMR group (30 lesions, 88.2%); however, this difference was not significant (p = 0.441). Overall complication did not differ significantly between the ESMR-L group and the EMR group (p = 0.774). There was one case of a remnant lesion in the ESMR-L group, which was managed by EMR after circumferential pre-cutting (EMR-P), and no recurrence has been detected in either the ESMR-L or EMR group.

CONCLUSIONS

ESMR-L and EMR procedures could have a similar excellent complete resection rate, if we select the endoscopic resection technique according to the characteristics of the small rectal NETs.

Rare tumors of the rectum. Narrative review

Most rectal neoplasms are adenocarcinomas, but there is a small percentage of tumors which are of other histological cell lines such as neuroendocrine tumors, sarcomas, lymphomas and squamous cell carcinomas, which have special characteristics and different treatments. We have reviewed these rare tumors of the rectum from a clinical and surgical point of view.

Which endoscopic treatment is the best for small rectal carcinoid tumors?

The incidence of rectal carcinoids is rising because of the widespread use of screening colonoscopy. Rectal carcinoids detected incidentally are usually in earlier stages at diagnosis. Rectal carcinoids estimated endoscopically as < 10 mm in diameter without atypical features and confined to the submucosal layer can be removed endoscopically. Here, we review the efficacy and safety of various endoscopic treatments for small rectal carcinoid tumors, including conventional polypectomy, endoscopic mucosal resection (EMR), cap-assisted EMR (or aspiration lumpectomy), endoscopic submucosal resection with ligating device, endoscopic submucosal dissection, and transanal endoscopic microsurgery. It is necessary to carefully choose an effective and safe primary resection method for complete histological resection.

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.