Rectal carcinoids are on the rise: early detection by screening endoscopy

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.

Local Excision Versus Radical Resection for 1- to 2-cm Neuroendocrine Tumors of the Rectum: A National Cancer Database Analysis

BACKGROUND

The optimal surgical management for 1- to 2-cm, nonmetastatic rectal neuroendocrine tumors remains unknown.

OBJECTIVE

We sought to determine overall survival and operative outcomes in patients who underwent local excision versus radical resection of rectal neuroendocrine tumors.

DESIGN

The National Cancer Database (2004-2013) was queried to identify patients with nonmetastatic rectal neuroendocrine tumors who underwent local excision or radical resection.

SETTING

The study included national data.

PATIENTS

There were 274 patients in the local excision group and 47 patients in the radical resection group.

MAIN OUTCOME MEASURES

The primary outcome was overall survival. Secondary outcomes included 30-day mortality, hospital length of stay, and procedural outcomes.

RESULTS

There were no differences in demographics between the 2 groups. Patients who underwent radical resection had slightly larger tumors with higher stage and grade. Patients undergoing local excision had higher rates of positive margins (8.23% vs 0%; p = 0.04). There were no deaths within 30 days in either group, but patients who had radical resection had longer median hospital length of stay (0 vs 3 d; p < 0.01). After adjusting with a Cox proportional hazards model, no difference was seen in survival between the 2 patient groups (HR = 2.39 (95% CI, 0.85-6.70); p = 0.10).

LIMITATIONS

There are several limitations, which include that this work is a retrospective review; the data set does not include variables such as depth of tumor invasion, which may influence surgical treatment or local recurrence rates; and patients were not randomly assigned to treatment groups.

CONCLUSIONS

There is no survival benefit to radical resection of 1- to 2-cm, nonmetastatic rectal neuroendocrine tumors. This suggests that local excision may be a feasible and less morbid option for intermediate-sized rectal neuroendocrine tumors. See Video Abstract at http://links.lww.com/DCR/A744.

Long-term outcomes according to additional treatments after endoscopic resection for rectal small neuroendocrine tumors

The present study aimed to investigate treatment strategies determining additional treatment after endoscopic resection (ER) of rectal neuroendocrine tumor (NET)s and long-term outcomes of endoscopically resected rectal NETs. We analyzed a total of 322 patients medical records of patients who underwent ER for rectal NETs. Rectal NETs initially resected as polyps and treated with conventional endoscopic mucosal resection (EMR) were observed more frequently in the non-curative group (P = 0.041 and P = 0.012, respectively). After ER, only 44 of the 142 patients (31.0%) who did not meet the criteria for curative resection received additional salvage treatment. In multivariate analysis, lesions diagnosed via biopsies (OR, 0.096; P = 0.002) or suspected as NETs initially (OR, 0.04; P = 0.001) were less likely to undergo additional treatment. Positive lymphovascular invasion (OR 61.971; P < 0.001), positive (OR 75.993; P < 0.001), or indeterminate (OR 13.203; P = 0.001) resection margins were more likely to undergo additional treatment. Although lymph node metastasis was found in 6 patients, none experienced local or metastatic tumor recurrence during the median follow-up of 40.49 months. Long-term outcomes after ER for rectal NETs were excellent. The prognosis showed favorable outcomes regardless of whether patients receive additional salvage treatments.

Prevalence of metastasis and survival of 788 patients with T1 rectal carcinoid tumors

BACKGROUND AND AIMS

Prevalence of rectal carcinoids is increasing, partly because of increased colorectal cancer screening. Local excision (endoscopic or transanal excision) is usually performed for small (<1-2 cm) rectal carcinoids, but data on clinical outcomes from large population-based U.S. studies are lacking. The aims of this study were to determine the prevalence of metastasis of resected small rectal carcinoid tumors using a large national cancer database and to evaluate the long-term survival of patients after local resection as compared with radical surgery.

METHODS

The Surveillance Epidemiology and End Results database was used to identify 788 patients with rectal T1 carcinoids <2 cm in size. Prevalence of metastases at initial diagnosis and risk factors for metastases were analyzed. Cancer-specific survival (CSS) was calculated.

RESULTS

A total of 727 patients (92.3%) had tumors ≤10 mm in diameter and 61 (7.7%) had tumors 11 to 19 mm. Overall, 12 patients (1.5%) had metastasis at the time of diagnosis with prevalence of 1.1% in lesions ≤10 mm and 6.6% in lesions 11 to 19 mm (P = .01). Survival of patients with T1 rectal carcinoids without metastasis was significantly better than those with metastasis (5-year CSS of 100% vs 78%, P < .001). Of 559 patients with T1N0M0 rectal carcinoids ≤10 mm, 5-year CSS was 100% in both groups who underwent local excision and those who underwent radical surgery.

CONCLUSIONS

Larger T1 rectal carcinoid tumors (11-19 mm) have significantly higher risk of lymph node metastases compared with those ≤10 mm. Survival is worse with metastatic disease. Local therapy is adequate for T1N0M0 rectal carcinoids ≤10 mm in size with excellent long-term outcomes.

Predictors of Metastases in Rectal Neuroendocrine Tumors: Results of a National Cohort Study

BACKGROUND

Rectal neuroendocrine tumors are often found incidentally. Local excision alone has been advocated for lesions ≤2 cm; however, the evidence base for this approach is limited.

OBJECTIVE

Associations among tumor size, degree of differentiation, and presence of distant metastatic disease were examined.

DESIGN

This was a retrospective cohort study.

SETTINGS

This study was conducted using a nationwide cohort.

PATIENTS

A total of 4893 patients with rectal neuroendocrine tumors were identified in the National Cancer Database (2006-2015).

MAIN OUTCOME MEASURES

Logistic regression analyses were used to evaluate associations among tumor size, degree of differentiation, and presence of regional and distant metastatic disease. Cut point analysis was performed to identify an optimal size threshold predictive of distant metastatic disease.

RESULTS

Of patients included for analysis, 3880 (79.3%) had well-differentiated tumors, 540 (11.0%) had moderately differentiated tumors, and 473 (9.7%) had poorly differentiated tumors. On logistic regression, increasing size was associated with a higher likelihood of pathologically confirmed lymph node involvement (among patients undergoing proctectomy), and both size and degree of differentiation were independently associated with a higher likelihood of distant metastatic disease. The association between tumor size and distant metastatic disease was stronger for well-differentiated and moderately differentiated tumors (OR = 1.4; p < 0.001 for both) than for poorly differentiated tumors (OR = 1.1; p = 0.010). For well-differentiated tumors, the optimal cut point for the presence of distant metastatic disease was 1.15 cm (area under the curve = 0.88; 88% sensitive and 88% specific). Tumors ≥1.15 cm in diameter were associated with a substantially increased incidence of distant metastatic disease (72/449 (13.8%)). For moderately differentiated tumors, the optimal cut point was also 1.15 cm (area under the curve = 0.87, 100% sensitive and 75% specific).

LIMITATIONS

This study was limited by its retrospective design.

CONCLUSIONS

Tumor size and degree of differentiation are predictive of regional and distant metastatic disease in rectal neuroendocrine tumors. Patients with tumors >1.15 cm are at substantial risk of distant metastasis and should be staged and managed accordingly. See Video Abstract at http://links.lww.com/DCR/A778.

[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.

Chromogranin A: From Laboratory to Clinical Aspects of Patients with Neuroendocrine Tumors

Background. Neuroendocrine tumors (NETs) are characterized by having behavior and prognosis that depend upon tumor histology, primary site, staging, and proliferative index. The symptoms associated with carcinoid syndrome and vasoactive intestinal peptide tumors are treated with octreotide acetate. The PROMID trial assesses the effect of octreotide LAR on the tumor growth in patients with well-differentiated metastatic midgut NETs. The CLARINET trial evaluates the effects of lanreotide in patients with nonfunctional, well-, or moderately differentiated metastatic enteropancreatic NETs. Everolimus has been approved for the treatment of advanced pancreatic NETs (pNETs) based on positive PFS effects, obtained in the treated group. Sunitinib is approved for the treatment of patients with progressive gastrointestinal stromal tumor or intolerance to imatinib, because a randomized study demonstrated that it improves PFS and overall survival in patients with advanced well-differentiated pNETs. In a phase II trial, pasireotide shows efficacy and tolerability in the treatment of patients with advanced NETs, whose symptoms of carcinoid syndrome were resistant to octreotide LAR. An open-label, phase II trial assesses the clinical activity of long-acting repeatable pasireotide in treatment-naive patients with metastatic grade 1 or 2 NETs. Even if the growth of the neoplasm was significantly inhibited, it is still unclear whether its antiproliferative action is greater than that of octreotide and lanreotide. Because new therapeutic options are needed to counter the natural behavior of neuroendocrine tumors, it would also be useful to have a biochemical marker that can be addressed better in the management of these patients. Chromogranin A is currently the most useful biomarker to establish diagnosis and has some utility in predicting disease recurrence, outcome, and efficacy of therapy.

Clinical outcomes of endoscopic mucosal resection for rectal neuroendocrine tumor

Background

The incidence of rectal neuroendocrine tumors (NETs) is rapidly increasing because of the frequent use of endoscopic screening for colorectal cancers. However, the clinical outcomes of endoscopic resection for rectal NETs are still unclear. The aim of this study was to assess the rates of histologically complete resection (H-CR) and recurrence after endoscopic mucosal resection (EMR) for rectal NETs.

Methods

A retrospective analysis was performed on patients who underwent EMR for rectal NETs between January 2002 and March 2015 at Seoul National University Hospital. Primary outcomes were H-CR and recurrence rates after endoscopic resection. H-CR was defined as the absence of tumor invasion in the lateral and deep margins of resected specimens.

Results

Among 277 patients, 243 (88%) were treated with conventional EMR, 23 (8%) with EMR using a dual-channel endoscope, and 11 (4%) with EMR after precutting. The median tumor size was 4.96 mm (range, 1–22) in diameter, and 264 (95%) lesions were confined to the mucosa and submucosal layer. The en-bloc resection rate was 99% and all patients achieved endoscopically complete resection. The H-CR rates were 75, 74, and 73% for conventional EMR, EMR using a dual-channel endoscope, and EMR after precutting, respectively. Multivariate analysis showed that H-CR was associated with tumor size regardless of endoscopic treatment modalities (p = 0.023). Of the 277 patients, 183 (66%) underwent at least 1 endoscopic follow-up. Three (2%) of these 183 patients had tumor recurrence, which was diagnosed at a median of 62.5 months (range 19–98) after endoscopic resection. There was 1 case of disease-related death, which occurred 167 months after endoscopic treatment because of bone marrow failure that resulted from tumor metastasis.

Conclusions

Although the en-bloc resection rate was 99% in rectal NETs, H-CR rates were 72–74% for various EMR procedures. H-CR may be associated with tumor size regardless of endoscopic treatment modalities.

Neuroendocrine neoplasms of rectum: A management update

The estimated annual incidence of R-NENs is 1.04 per 100,000 persons although the real incidence may be underestimated, as not all R-NEN are systematically reported in registers. Also the prevalence has increased substantially, reflecting the rising incidence and indolent nature of R-NENs, showing the highest prevalence increase among all site of origin of NENs. The size of the tumor reveals the behavior of R-NENs where the risk for metastatic spread increases for lesions > 10 mm. Applying the WHO 2010 grading system to whole NENs originating in the gastroenteropancreatic system, R-NENs are classified as Well-Differentiated Neuroendocrine Tumors (WD-NET), which contain NET G1 and NET G2, and Poorly-Differentiated Carcinomas (PD-NEC) enclosing only G3 neoplasms for which the term carcinoma is applied. The treatment is endoscopic resection in most cases: conventional polypectomy or endoscopic mucosal resection (EMR) for smaller lesions or endoscopic submucosal resection with a ligation device (ESMR-L), cap-assisted EMR (EMR-C) and endoscopic submucosal dissection (ESD). However it is important to know when the endoscopic treatment is not enough, and surgical treatment is indicated, or when the latter could be unnecessary. For PD-NECs, it has recently been demonstrated that chemoradiotherapy is associated with a similar long-term survival to that obtained with surgery. As well, new targeted-agents chemotherapy may be indicated for metastatic WD-NETs.

Ileocolonic neuroendocrine tumours identified in the English bowel cancer screening programme

AIM

Ileocolonic neuroendocrine tumours (NETs) are diagnosed as part of bowel cancer screening programmes (BCSPs). The aim of this study was to identify and characterize NETs diagnosed within the English BCSP, a double-screen programme that uses guaic faecal occult blood test (gFOBT) screening and colonoscopy, by interrogating the national colorectal screening database and validating the findings with individual BCSP centres.

METHOD

The Exeter database was interrogated by running queries to identify participants with coded NETs (from the start of the programme in July 2006 - 1 December 2014). A written proforma was sent to the responsible BCSP clinician for validation and characterization.

RESULTS

During this period, 13 061 716 participants were adequately screened using gFOBTs, and 259 765 participants had definitively abnormal results. There were 146 unique participants with NET-related codes from 216 707 BCSP colonoscopies. The diagnosis rates per 100 000 colonoscopies were 29 rectal, 18 colonic and 11 ileal NETs. The majority of rectal NETs had Grade 1 (80%) and Stage T1 (85.1%) disease. Over half of ileal NETs (53.6%) in this study had invasive disease, with 85.2% having nodal and 36.1% having metastastatic disease.

CONCLUSION

The current study highlights the rate of colorectal NETs diagnosed in the English BCSP. These data highlight a higher-than-anticipated incidence, and the potential additional benefit of BCSPs in identifying occult NETs.

Long-term Outcome of Small, Incidentally Detected Rectal Neuroendocrine Tumors Removed by Simple Excisional Biopsy Compared With the Advanced Endoscopic Resection During Screening Colonoscopy

BACKGROUND

Incidental, small rectal neuroendocrine tumors during colonoscopy screening are sometimes removed using biopsy forceps. Few studies have examined the clinical course of rectal neuroendocrine tumors removed by simple excisional biopsy.

OBJECTIVE

We investigated the long-term outcome of rectal neuroendocrine tumors removed by simple excisional biopsy compared with standard endoscopic resection.

DESIGN

This was a cohort study.

SETTINGS

This study was performed at a healthcare center in Korea.

PATIENTS

We enrolled patients with rectal neuroendocrine tumors detected during a screening colonoscopy between 2003 and 2015.

MAIN OUTCOME MEASURES

The clinical characteristics and long-term outcomes (overall survival and disease-free survival) of small neuroendocrine tumors <10 mm were compared between the simple excisional biopsy group and advanced endoscopic resection group.

RESULTS

In total, 166 patients were diagnosed with rectal neuroendocrine tumors (≤5 mm, n = 100; 6-9 mm, n = 50; 10-19 mm, n = 15; ≥20 mm, n = 1). Among the 150 patients with neuroendocrine tumors <10 mm, follow-up endoscopy was performed on 99 (59.6%). All of the tumors were confined to the mucosa or submucosa. Thirty-one and 68 patients were included in the simple excisional biopsy and advanced endoscopic resection groups. The overall follow-up duration was 6.5 years (range, 1.0-12.8 y). Neither overall nor disease-related death occurred. Two patients exhibited local recurrence (6.5%, at 8 and 11 y) in the simple excisional biopsy group and 1 patient (1.5%, at 7 y) in the advanced endoscopic resection group, resulting in no significant difference (p = 0.37). All of the recurrences were diagnosed >5 years from initial diagnosis and successfully treated endoscopically.

LIMITATIONS

More long-term data should be warranted.

CONCLUSIONS

The long-term outcome of small rectal neuroendocrine tumors <10 mm removed by simple excisional biopsy was excellent. Neither overall survival nor disease-free survival significantly differed between the simple excisional biopsy group and the advanced endoscopic resection group. Thus, simple excisional biopsy and long-term follow-up can be cautiously applied for small rectal neuroendocrine tumors in clinical practice. See Video Abstract at http://links.lww.com/DCR/A406.

A 10-year History of a Diminutive Rectal Neuroendocrine Tumor

A 39-year-old woman underwent a preoperative diagnostic colonoscopy for cervical cancer. A 3-mm neuroendocrine tumor (NET) was incidentally detected in the rectum. The NET was observed via 7 colonoscopies over 10 years while giving priority to treating the cervical cancer. Complete cervical cancer remission was confirmed at the 10-year follow-up examination; therefore, endoscopic treatment for the NET was subsequently performed. The NET showed almost no change in either size or morphology over the 10-year period. This case illustrates the possible very-slow progression of a small NET, suggesting its benign behavior.

Prognostic Factors for Locoregional Recurrence in Neuroendocrine Tumors of the Rectum

BACKGROUND

Optimal management of rectal neuroendocrine tumors is not yet well defined. Various pathologic factors, particularly tumor size, have been proposed as prognostic markers.

OBJECTIVE

We characterized sequential patients diagnosed with rectal neuroendocrine tumors in a population-based setting to determine whether tumor size and other pathologic markers could be useful in guiding locoregional management.

DESIGN

This study is a retrospective analysis of data from the British Columbia provincial cancer registry.

SETTINGS

The study was conducted at a tertiary care center.

PATIENTS

Sequential patients diagnosed with rectal neuroendocrine tumors between 1999 and 2011 were identified. Neuroendocrine tumors were classified as G1 and G2 tumors with a Ki-67 ≤20% and/or mitotic count ≤20 per high-power field.

MAIN OUTCOME MEASURES

Baseline clinicopathologic data including TNM staging, depth of invasion, tumor size, treatment modalities, and outcomes including survival data were measured.

RESULTS

Of 91 rectal neuroendocrine tumors, the median patient age was 58 years, and 35 were men. Median tumor size was 6 mm. Median length of follow-up was 58.1 months, with 3 patients presenting with stage IV disease. Treatment included local ablation (n = 5), local excision (n = 79), surgical resection (n = 4), and pelvic radiation (n = 1; T3N1 tumor). Final margin status was positive in 17 cases. Local relapse occurred in 8 cases and 1 relapse to bone 13 months after T3N1 tumor resection. Univariate analysis demonstrated an association between local relapse and Ki-67, mitotic count, grade, and lymphovascular invasion (p < 0.01). Larger tumor size was associated with decreased disease-free survival.

LIMITATIONS

Sample size was 91 patients in the whole provincial population over a 13-year time period because of the low incidence of rectal neuroendocrine tumors.

CONCLUSIONS

In this population-based cohort, rectal neuroendocrine tumors generally presented with small, early tumors and were treated with local excision or surgical resection without pelvic radiation. Pathologic markers play a role in risk stratification and prognostication. See Video Abstract at http://links.lww.com/DCR/A514.

Transanal Endoscopic Microsurgery for Patients with Rare Rectal Tumors

BACKGROUND

Transanal endoscopic microsurgery (TEM) has been accepted worldwide for the treatment of local rectal lesions. Rare rectal tumors consist of several different types of malignant or benign tumors. Surgical management is considered to be the only curative option. The aim of this study is to investigate the role of TEM in the treatment of rare rectal tumors.

MATERIALS AND METHODS

A total of 147 patients with rare rectal tumors underwent TEM in our center from April 2006 to May 2017. Clinical data were collected and a retrospective accurate database was constructed. Demographic characteristics, operative details, tumor details, complications, and follow-up data were analyzed.

RESULTS

Seventy-eight patients were male. Mean tumor diameter was 1.2 ± 0.7 cm and mean distance from the anal verge was 6.6 ± 2.3 cm. Full-thickness and complete resection with negative margins was achieved in all patients. Complications occurred in 3 patients during surgery and in 20 patients after surgery. Histopathologic results were neuroendocrine tumors in 104 patients; gastrointestinal stromal tumors in 35; melanoma, lymphoma, and leiomyoma each in 2; lipoma, and squamous carcinoma each in 1. One hundred thirty-five patients were followed up for 49.3 ± 33.2 months. Two patients died, 1 had local recurrence and 1 had a rectovaginal fistula 1 month after surgery. No local recurrence or metastasis, or fecal incontinence was observed in the remaining patients.

CONCLUSION

TEM is an optimal treatment option for selected rare rectal tumors. The complication rate is low and the therapeutic effect is satisfactory.

Local resection of rectal neuroendocrine tumor with first clinical manifestation of giant liver metastasis by transanal endoscopic microsurgery: A case report

RATIONALE

Rectal neuroendocrine tumor (NET) is a relatively rare tumor. Well-differentiated NETs (G1 and G2) rarely display distant metastasis at initial diagnosis. Currently, treatment for the primary lesions of rectal NETs with liver metastasis remains controversial. The liver metastasis was resected in local hospital. Transanal endoscopic microsurgery (TEM) has emerged as an effective minimally invasive surgery for local resection of lower rectal lesions. Herein, we reported the initial application of TEM to remove the rectal primary lesion in patients with low rectal NETs (G2) with giant liver metastases.

PATIENT CONCERNS

The patient, a 45-year-old woman, was primarily diagnosed with hepatocellular carcinoma and underwent curative resection of a giant liver lesion in a local hospital. Nevertheless, the postoperative pathologic examination revealed that the lesion was an NET (G2). The colonoscopy then showed a nodule 1.4 cm in diameter, 4 cm above the anal verge, located on the anterior wall of the rectum. The biopsy revealed that the nodule was also an NET (G2). However, the patient did not consent to abdominoperineal resection based on concerns for quality of life.

DIAGNOSES

Rectal NET with liver metastasis.

INTERVENTIONS

The patient underwent curative resection of liver metastasis. And, TEM was adopted to resect the primary tumor in rectum.

OUTCOMES

The patient has been disease-free for 2 years with a good quality of life and presents no local recurrence in the rectum.

LESSONS

TEM is an appropriate palliative operation for therapy of rectal NETs with distant metastases, especially for primary rectal NETs located in low rectal.

Early Gastroenteropancreatic Neuroendocrine Tumors: Endoscopic Therapy and Surveillance

Neuroendocrine neoplasias (NEN) of the stomach, duodenum, pancreas, appendix, or rectum that are ≤1 cm in size as well as well-differentiated with World Health Organization grade 1 (G1) can be considered 'early' neuroendocrine tumors; they have a very good prognosis. Regarding prognosis, neuroendocrine tumors (NET) G1 must be distinguished from well-differentiated NET G2 and poorly differentiated neuroendocrine carcinomas (NEC) G3. NET are increasing, with a rise in the age-adjusted incidence in the USA by about 700% in the last 40 years. Earlier diagnosis of NET is one of the main epidemiological changes of clinically detected NEN. The general availability of high-resolution endoscopy and advanced radiological imaging techniques has contributed to a shift in the discovery to smaller-sized (≤10 mm) gastrointestinal and pancreatic NET and earlier tumor stages at diagnosis. Thus, screening colonoscopy is effective in the early diagnosis not only of colorectal adenomas and adenocarcinomas but also of rectal NET. Endoscopic resection is the treatment of choice in NET G1 of the stomach, duodenum (despite gastrinoma), and rectum that are ≤10 mm in size, do not infiltrate the muscularis propria (T1), and do not show angioinvasion (V0, L0). Similarly, histologically proven, early pancreatic NET G1 (≤10 mm) may be managed conservatively by regular surveillance. In contrast, small (≤1 cm) NET G1 of the jejunum or ileum are not 'early' tumors and have to be resected surgically with lymph node dissection.

A rectal neuroendocrine neoplasm

The incidence of gastric and rectal carcinoids is increasing. This is probably due to endoscopic screening. The prognosis is primarily dependent upon tumor size, aggressiveness (pathology, Ki-67), metastatic disease and stage. However, neuroendocrine carcinoma usually behaves as an adenocarcinoma.

Pediatric Neuroendocrine Carcinoid Tumors: Review of Diagnostic Imaging Findings and Recent Advances

OBJECTIVE

Although rare, pediatric neuroendocrine tumors including carcinoid tumor have increased in incidence over the past few decades. Despite increased recognition, survival rates have not significantly improved. Earlier detection of these tumors is necessary to improve clinical outcomes. This article discusses imaging approaches for detecting pediatric carcinoid tumors including anatomic imaging methods such as CT and MRI as well as functional imaging methods targeting the somatostatin receptor including ¹¹¹In-labeled octreotide and newer ⁶⁸Ga-based radiotracers that may hold promise in hybrid PET/CT or PET/MRI.

CONCLUSION

Improvements in functional imaging with novel somatostatin receptor-specific radiotracers along with fused functional and anatomic imaging have substantially improved the clinical detection of carcinoid tumors. Although rare, these tumors are encountered in children, and an awareness of the appropriate use of various imaging methods is essential for pediatric specialists. Further research is needed to ascertain the diagnostic value of newer imaging methods and radiotracer-based treatment approaches, especially in the pediatric population.

Frequent Presence of Lymphovascular Invasion in Small Rectal Neuroendocrine Tumors on Immunohistochemical Analysis

Rectal neuroendocrine tumors (RNETs) have become common in recent years and are good candidates for endoscopic resection (ER). To achieve clear resection margins, more advanced techniques such as endoscopic submucosal dissection, endoscopic submucosal resection with a ligation device, and cap-assisted endoscopic mucosal resection are available for ER. After ER, lymphovascular invasion (LVI) is regarded as an important predictor of nodal metastasis. Previous studies have shown that small RNETs with LVI were uncommon (0-8.3%). However, using immunohistochemical analysis, a recent study revealed the frequent occurrence of LVI in small RNETs in a systematic manner (46.7%). There is a possibility that the actual detection rate of LVI in small RNETs is not always evaluated accurately because of the limited detection sensitivity of conventional hematoxylin-eosin staining. In addition, the correlation between LVI detected using immunohistochemical analysis and the development of metastasis remains unclear. Further prospective studies are required to clarify the role of LVI detected using immunohistochemical analysis.

Evaluation of the risk factors associated with rectal neuroendocrine tumors: a big data analytic study from a health screening center

BACKGROUND

Rectal neuroendocrine tumor (NET) is the most common NET in Asia. The risk factors associated with rectal NETs are unclear because of the overall low incidence rate of these tumors and the associated difficulty in conducting large epidemiological studies on rare cases. The aim of this study was to exploit the benefits of big data analytics to assess the risk factors associated with rectal NET.

METHODS

A retrospective case-control study was conducted, including 102 patients with histologically confirmed rectal NETs and 52,583 healthy controls who underwent screening colonoscopy at the Center for Health Promotion of the Samsung Medical Center in Korea between January 2002 and December 2012. Information on different risk factors was collected and logistic regression analysis applied to identify predictive factors.

RESULTS

Four factors were significantly associated with rectal NET: higher levels of cholesterol [odds ratio (OR) = 1.007, 95 % confidence interval (CI), 1.001-1.013, p = 0.016] and ferritin (OR = 1.502, 95 % CI, 1.167-1.935, p = 0.002), presence of metabolic syndrome (OR = 1.768, 95 % CI, 1.071-2.918, p = 0.026), and family history of cancer among first-degree relatives (OR = 1.664, 95 % CI, 1.019-2.718, p = 0.042).

CONCLUSION

The findings of our study demonstrate the benefits of using big data analytics for research and clinical risk factor studies. Specifically, in this study, this analytical method was applied to identify higher levels of serum cholesterol and ferritin, metabolic syndrome, and family history of cancer as factors that may explain the increasing incidence and prevalence of rectal NET.

Lymphovascular invasion in more than one-quarter of small rectal neuroendocrine tumors

AIM

To identify the frequency, clinicopathological risk factors, and prognostic significance of lymphovascular invasion (LVI) in endoscopically resected small rectal neuroendocrine tumors (NETs).

METHODS

Between June 2005 and December 2015, 104 cases of endoscopically resected small (≤ 1 cm) rectal NET specimens at Hallym University Sacred Heart Hospital in Korea were retrospectively evaluated. We compared the detected rate of LVI in small rectal NET specimens by two methods: hematoxylin and eosin (H&E) and ancillary immunohistochemical staining (D2-40 and Elastica van Gieson); in addition, LVI detection rate difference between endoscopic procedures were also evaluated. Patient characteristics, prognosis and endoscopic resection results were reviewed by medical charts.

RESULTS

We observed LVI rates of 25.0% and 27.9% through H&E and ancillary immunohistochemical staining. The concordance rate between H&E and ancillary studies was 81.7% for detection of LVI, which showed statistically strong agreement between two methods (κ = 0.531, P < 0.001). Two endoscopic methods were studied, including endoscopic submucosal resection with a ligation device and endoscopic submucosal dissection, and no statistically significant difference in the LVI detection rate was detected between the two (26.3% and 26.8%, P = 0.955). LVI was associated with large tumor size (> 5 mm, P = 0.007), tumor grade 2 (P = 0.006). Among those factors, tumor grade 2 was the only independent predictive factor for the presence of LVI (HR = 4.195, 95%CI: 1.321-12.692, P = 0.015). No recurrence was observed over 28.8 mo regardless of the presence of LVI.

CONCLUSION

LVI may be present in a high percentage of small rectal NETs, which may not be associated with short-term prognosis.

Enhanced detection of lymphovascular invasion in small rectal neuroendocrine tumors using D2-40 and Elastica van Gieson immunohistochemical analysis

Rectal neuroendocrine tumor (RNET) lymphovascular invasion (LVI) is regarded as an important predictor of nodal metastasis after endoscopic resection (ER). However, little is known about the frequency of immunohistochemical detection of LVI in RNETs. This study was performed to establish the actual detection of LVI rate in RNETs ≤10 mm and to evaluate associated clinical outcomes. We retrospectively reviewed the records for 98 consecutive patients treated by ER with a total of 102 RNETs ≤10 mm. Tissue sections were labeled with hematoxylin–eosin (HE) stain, the D2‐40 monoclonal antibody to evaluate lymphatic invasion, and Elastica van Gieson (EVG) stain to detect venous invasion. LVI detection rate by HE versus immunohistochemical analysis was compared. Follow‐up findings and clinical outcomes were also evaluated for 91 patients who were followed for ≥12 months. Lymphatic and venous invasion were detected using HE staining alone in 6.9% and 3.9% of patients, respectively, whereas they were detected using D2‐40 and EVG staining in 20.6% and 47.1% of the patients, respectively. Thus, the LVI detection frequency using D2‐40 and EVG staining (56.9%) was significantly higher than with HE (8.8%). Two out of seven patients who required additional surgery had regional lymph node metastases. However, among the 84 patients who were followed up without surgery, no distant metastases or recurrences were detected. Compared with HE staining, immunohistochemical analysis significantly increased the frequency of LVI detection in RNETs ≤10 mm. However, the clinical impact of LVIs detected using immunohistochemical analysis remains unclear. Clarification of the actual role of LVI using immunohistochemical analysis requires a patient long‐term follow‐up and outcomes.

Early diagnosis and treatment of gastrointestinal neuroendocrine tumors

The aim of the present retrospective analysis on the macroscopic appearance and pathological characteristics of gastrointestinal neuroendocrine tumors (NETs) was to investigate methods for their early diagnosis and treatment. A total of 78 patients were divided into submucosal NET and deeper invasion NET groups, according to the depth of tumor invasion exhibited by the patients. The clinicopathological characteristics and survival time of the NET patients were analyzed and compared. The pathological characteristics of the submucosal NETs group were investigated according to the diameter of the tumor (≤5.0 mm, 5.1-10.0 mm or >10.0 mm). The depth of invasion at diagnosis was observed to significantly correlate with histopathological classification, diameter of the tumor, macroscopic appearance, growth pattern, lymphatic-vascular involvement, lymph node (LN) metastasis and distant metastasis. In the submucosal NETs group, high-grade tumors with lymphatic or venule invasion and distant metastasis were associated with an increased risk of nodal metastases. In patients with minute tumors (≤5.0 mm), no lymphatic-vascular involvement, LN or distant metastasis was observed. By contrast, patients with tumors measuring 5.1-10.0 mm in diameter exhibited high lymphatic-vascular involvement and LN metastasis rates (46.2 and 30.8%, respectively). Survival time was significantly longer in patients with submucosal NETs compared with deeper invasion NETs and in patients with NET G1 and NET G2 compared with NEC. The results of the present study indicate that gastrointestinal submucosal NETs are closely associated with a slightly elevated macroscopic type, low-grade tumors and a small diameter. These features may contribute to early diagnosis of gastrointestinal NETs. Therefore, a tumor diameter of <5.0 mm, with slightly elevated macroscopic appearance may indicate an absolute requirement for endoscopic resection, while tumors measuring 5.1-10.0 mm in diameter must be considered carefully.

Review article: the investigation and management of rectal neuroendocrine tumours

BACKGROUND

Rectal neuroendocrine tumours (NETs) are increasingly identified at endoscopy possibly as a result of bowel cancer screening programmes.

AIM

To present a review of the literature to aid clinicians in the diagnosis and management of rectal neuroendocrine tumours.

METHODS

A literature search was conducted through MEDLINE using search terms: rectal, rectum, carcinoid, NET, therapy, endoscopy, mucosal resection, submucosal dissection. Relevant articles were identified through manual review with reference lists reviewed for additional articles.

RESULTS

The incidence of rectal neuroendocrine tumours is approximately 1 per 100 000 population per year with the majority (80-90%) being <1 cm and localised to the submucosa. Metastatic disease is infrequent (<20%) with risk factors including size, atypical appearance, grade and depth of invasion. The primary resection modality influences complete resection rates and the need for secondary therapy. A thorough pre-resection diagnostic work up is required for lesions that are at higher risk of invasion and metastasis. Device-assisted endoscopic mucosal resection and endoscopic submucosal dissection are used to resect localised rectal neuroendocrine tumours <2 cm. Transanal surgery is also used to resect localised 1-2 cm rectal neuroendocrine tumours. Oncological surgical resection is used for rectal neuroendocrine tumours that are >2 cm or with invasion and regional disease. The treatment of advanced disease is multimodal.

CONCLUSIONS

The long-term tumour biology of small rectal neuroendocrine tumours remains unclear. There is uncertain impact from bowel cancer screening programmes on rectal neuroendocrine tumour incidence, morbidity and mortality. Referral to neuroendocrine tumour centres for patients with locally advanced disease or metastatic disease is recommended.

Endoscopic submucosal dissection versus transanal local excision for rectal carcinoid: a comparative study

Aim

The aim of this study is to compare the short-term clinical outcomes between endoscopic submucosal dissection and transanal local excision for rectal carcinoid tumors.

Methods

Between 2007 and 2012, 31 patients with rectal carcinoid underwent endoscopic submucosal dissection at our hospital. They were compared with a matched cohort of 23 patients who underwent transanal local excision for rectal carcinoid between 2007 and 2012. Short-term clinical outcomes including surgical parameters, postoperative recovery, and oncologic outcomes were compared between the two groups.

Results

The mean size of tumors was significantly bigger in the transanal local excision group (0.8 ± 0.2 versus 1.1 ± 0.5 cm; P = 0.018). En bloc resection was achieved for 30 patients (97 %) in the endoscopic submucosal dissection group and all the patients in the transanal local excision group. The operation time was longer in the transanal local excision than that in the endoscopic submucosal dissection group (40.0 ± 22.7 min versus 12.2 ± 5.3 min; P < 0.001). Complications in the transanal local excision group were five cases of acute retention of urine. There was no local recurrence or distant metastasis in either group during the follow-up period.

Conclusion

For the treatment of rectal carcinoid tumors with diameter <1 cm, endoscopic submucosal dissection has better short-term clinical outcomes than transanal local excision in terms of faster recovery and possibly a lower morbidity rate. Transanal local excision may be the first therapeutic choice of scar-embedded rectal carcinoid tumors.

Obturator Canal Lymph Node Metastasis from Rectal Carcinoid Tumors: Total Mesorectal Excision May Be Insufficient

BACKGROUND

Optimal surgical treatment for small early rectal carcinoids is controversial. Large tumors (greater than 2 cm) and those with imaging evidence of lymph node metastasis are generally treated by low anterior resection (LAR) with total mesorectal excision (TME). We first observed and reported that midgut carcinoid with extensive mesenteric lymphadenopathy often develops alternated lymphatic drainage pathways. We hypothesize that rectal carcinoids have the same potential to develop alternated lymphatic pathways outside the mesorectal envelope, which allows tumor deposits to be missed by traditional TME.

METHODS

Twenty-two consecutive rectal carcinoid surgical patient charts were reviewed to determine if alternated lymphatic drainage occurred and resulted in extra-mesorectal metastasis. We attempted to identify any risk factor(s) that may lead to developing such alternated lymphatic drainage pathways.

RESULTS

Thirteen patients underwent initial LAR with TME (13/22, 59 %) and nine underwent a staged debulking for locoregional residual disease or regional/distant metastasis after previous resection (9/22, 41 %). Fourteen (14/22, 64 %) underwent radio-guided surgery in attempt to achieve a higher level of pelvic/distant metastatic disease detection and debulking. Six patients (6/22, 27 %) had obturator canal lymph node metastases confirmed histologically.

CONCLUSIONS

Based on our study, at least 27 % of rectal carcinoid patients may have extra-mesorectal metastasis that would be missed by the traditional TME. Radio-guided surgery can identify and remove such metastasis. The effect of having such extra-mesorectal metastasis and its surgical removal on long-term survival has yet to be determined.

Multiple rectal neuroendocrine tumors: report of five cases

Carcinoids are slow growing neuroendocrine tumors (NET) originating in the enterochromaffin cells of the gastrointestinal tract. In previous studies, rectal NET comprised only about 1% of all anorectal neoplasms; however, the incidence of rectal NET has shown a recent increase. Typically, rectal NET presents as a single subepithelial nodule, and multicentricity of rectal NETs is rare, with reported incidence of 2-4.5%. Due to the rarity of multiple rectal NETs, there is no consensus or guidelines for treatment of multiple rectal NETs. However, NETs of the rectum that are less than 10 mm in diameter and do not infiltrate the muscularis propria, without distant metastasis, can be removed by endoscopy, as with solitary rectal NET. We encountered five cases of multiple rectal NETs which were treated successfully by endoscopy.

Effectiveness of Endoscopic Treatment for Gastrointestinal Neuroendocrine Tumors: A Retrospective Study

Several recent studies have explored efficacy and safety of different endoscopic treatments for gastrointestinal neuroendocrine tumors (GI-NETs). However, there is no definitive consensus regarding the best endoscopic approach for GI-NETs treatment. Therefore, the present study was conducted to investigate the application of various endoscopic techniques for the treatment of GI-NETs according to the previous conclusions and to summarize the optimal endoscopic modalities for GI-NETs. Ninety-eight patients with 100 GI-NETs removed by endoscopic therapies were reviewed. The pathological complete resection rate (PCRR), complication, local recurrence, and factors possibly associated with the pathological complete resection were analyzed. Twenty-two patients were treated by conventional polypectomy (including 6 cold biopsy forceps polypectomy and 16 snare polypectomy with electrocauterization), 41 by endoscopic mucosal resection (EMR), and 35 by endoscopic submucosal dissection (ESD). The PCRRs of conventional polypectomy, EMR, and ESD were 86.4%, 75.6%, and 85.7%, respectively. Sixteen GI-NETs that had a polypoid appearance, with a mean tumor size of 5.2 mm, were removed by snare polypectomy (PCRR 93.8%). The complication rates of conventional polypectomy, EMR, and ESD were 0.0% (0/22), 2.4% (1/41), and 2.9% (1/35), respectively. There were 2 local recurrences after cold biopsy forceps polypectomy treatment and no local recurrences in the EMR and ESD groups (P = 0.049). The results showed that PCRR was only associated with the depth of invasion (P = 0.038). Endoscopic resection of GI-NETs is safe and effective in properly selected patients. For submucosal GI-NETs, ESD was a feasible modality, with a higher PCRR compared with EMR. For ≤5 mm polypoid-like NETs, snare polypectomy with electrocauterization was a simple procedure with a high PCRR.

Benign and malignant tumors of the rectum and perirectal region

Although most rectal masses are histologically characterized as adenocarcinomas, the rectum and perirectal region can be affected by a wide variety of tumors and tumor-like conditions that can mimic the symptoms caused by rectal adenocarcinoma, including mucosal or submucosal rectal tumors such as lymphoma, gastrointestinal stromal tumor, leiomyosarcoma, neuroendocrine tumor, hemangioma, and melanoma, as well as tumors of the perirectal region such as developmental cyst, neurogenic tumor, osseous tumor, and other miscellaneous conditions. As a group, tumors of the rectum are considerably different from the group of tumors that arise in the perirectal region: they are most often neoplastic, symptomatic, and malignant, whereas tumors arising in the perirectal region are most commonly congenital, asymptomatic, and benign. Proctoscopy with biopsy is the most important method for the diagnosis of rectal tumors, but this procedure cannot determine the precise intramural extension of a rectal tumor and cannot accurately distinguish submucosal and intramural tumors from extramural tumors. Cross-sectional imaging, especially transrectal ultrasound and magnetic resonance imaging, allows evaluation of the entire bowel wall thickness and the perirectal tissues, helping further characterize these tumors. Recognition of the existence of these masses and their key clinical and imaging features is crucial for clinicians to accurately diagnose and appropriately manage these conditions.

[Rectal neuroendocrine tumors: endoscopic therapy]

Clinically detected neuroendocrine neoplasms of the rectum have increased 10- to 30-fold in frequency over the past 45 years in Germany. Endoscopic ultrasonography is the method of choice for exact determination of the size of the tumor, depth of infiltration and detection of local lymph node metastases. Well-differentiated neuroendocrine tumors ≤ 10.0 mm in size that do not infiltrate the muscularis propria can be endoscopically resected. In the case of lymphatic or blood vessel invasion or spread to lymph nodes, surgical lymph node dissection is indicated. The management of well-differentiated, neuroendocrine rectal tumors 10.1-20 mm in size is still a matter of debate. Old age and multimorbidity favor a conservative endoscopic approach; however, in the case of fit young patients, surgical management has to be considered. For neuroendocrine rectal neoplasms ≥ 20 mm in size, the risk of metastatic spread increases to 60-80 % indicating that an endoscopic resection is not adequate. Due to the introduction of screening colonoscopy, neuroendocrine rectal tumors are nowadays diagnosed mostly at a prognostically favorable early stage.

Clinical impact of atypical endoscopic features in rectal neuroendocrine tumors

AIM: To validate the association between atypical endoscopic features and lymph node metastasis (LNM).

METHODS: A total of 247 patients with rectal neuroendocrine tumors (NETs) were analyzed. Endoscopic images were reviewed independently by two endoscopists, each of whom classified tumors by sized and endoscopic features, such as shape, color, and surface change (kappa coefficient 0.76 for inter-observer agreement). All of patients underwent computed tomography scans of abdomen and pelvis for evaluation of LNM. Univariate and multivariate analyses were performed to identify the factors associated with LNM. Additionally, the association between endoscopic atypical features and immunohistochemical staining of tumors was analyzed.

RESULTS: Of 247 patients, 156 (63.2%) were male and 15 (6.1%) were showed positive for LNM. On univariate analysis, tumor size (P < 0.001), shape (P < 0.001), color (P < 0.001) and surface changes (P < 0.001) were significantly associated with LNM. On multivariate analysis, tumor size (OR = 11.53, 95%CI: 2.51-52.93, P = 0.002) and atypical surface (OR = 27.44, 95%CI: 5.96-126.34, P < 0.001) changes were independent risk factors for LNM. The likelihood of atypical endoscopic features increased as tumor size increased. Atypical endoscopic features were associated with LNM in rectal NETs < 10 mm (P = 0.005) and 10-19 mm (P = 0.041) in diameter. Immunohistochemical staining showed that the rate of atypical endoscopic features was higher in non L-cell tumors.

CONCLUSION: Atypical endoscopic features as well as tumor size are predictive factors of LNM in patients with rectal NETs.

Excellent prognosis following endoscopic resection of patients with rectal neuroendocrine tumors despite the frequent presence of lymphovascular invasion

BACKGROUND

Endoscopic resection (ER) has been increasingly used for the treatment of rectal neuroendocrine tumors (NETs); however, only limited data are available on its long-term outcomes. This study analyzed the long-term outcomes of rectal NETs treated by ER and characterized potential risk factors for metastasis in these cases, with emphasis on lymphovascular invasion.

METHODS

We retrospectively analyzed the clinicopathological features and outcomes of 86 patients with 90 rectal NETs who had been treated by ER. Lymphovascular invasion was reevaluated using elastic-staining and double-staining immunohistochemistry.

RESULTS

En bloc resection with tumor-free margins was achieved in 87 lesions (96.7%). The median tumor size was 5 mm (range 2-13), and all the lesions were confined to the submucosal layer. The Ki-67 index was less than 3% in all the lesions, which were therefore classified as NET G1. Elastic-staining and double-staining immunohistochemistry revealed the presence of lymphatic and venous invasion in 23 (25.6%) and 35 lesions (36.7%), respectively. Collectively, lymphatic and/or vascular invasion was identified in 42 lesions (46.7%). All cases were followed up without additional surgery, and no metastasis or recurrence was detected during the median follow-up period of 67.5 months.

CONCLUSIONS

This study showed an excellent long-term prognosis following ER of patients with rectal NETs, confirming that ER is a valid treatment option for small rectal NETs. The present study also revealed highly prevalent lymphovascular invasion even in minute rectal NETs; this observation raises a question regarding its significance as a risk factor for metastasis.

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.

Endoscopic submucosal dissection for treatment of gastrointestinal neuroendocrine neoplasms: Analysis of 28 cases and a literature review

AIM: To assess the clinical efficacy and safety of endoscopic submucosal dissection (ESD) for gastrointestinal neuroendocrine neoplasms.

METHODS: A retrospective analysis was performed for 28 patients with gastrointestinal neuroendocrine neoplasms who underwent endoscopic therapy between May 2012 and February 2015. All patients underwent ESD. Endoscopic manifestations were summarized, and the related literature was reviewed in terms of curative effects and complications.

RESULTS: Twenty-eight cases were all successfully treated by ESD. All lesions were resected with lateral and basal resection margins free of tumor cells. Among all the cases, two had delayed massive bleeding and the bleeding rate was 7.1% (2/28). No complications such as perforation and infection occurred. No residual lesion or recurrence occurred during the follow-up period of 3-36 mo.

CONCLUSION: ESD is safe and effective in the treatment of patients with gastrointestinal neuroendocrine neoplasms (less than or equal to 20 mm) without muscularis propria invasion.

Full-thickness excision using transanal endoscopic microsurgery for treatment of rectal neuroendocrine tumors

AIM: To assess the efficacy of full-thickness excision using transanal endoscopic microsurgery (TEM) in the treatment of rectal neuroendocrine tumors.

METHODS: We analyzed the data of all rectal neuroendocrine tumor patients who underwent local full-thickness excision using TEM between December 2006 and December 2014 at our department. Data collected included patient demographics, tumor characteristics, operative details, postoperative outcomes, pathologic findings, and follow-ups.

RESULTS: Full-thickness excision using TEM was performed as a primary excision (n = 38) or as complete surgery after incomplete resection by endoscopic polypectomy (n = 21). The mean size of a primary tumor was 0.96 ± 0.21 cm, and the mean distance of the tumor from the anal verge was 8.4 ± 1.4 cm. The mean duration of the operation was 57.6 ± 13.7 min, and the mean blood loss was 13.5 ± 6.6 mL. No minor morbidities, transient fecal incontinence, or wound dehiscence was found. Histopathologically, all tumors showed typical histology without lymphatic or vessel infiltration, and both deep and lateral surgical margins were completely free of tumors. Among 21 cases of complete surgery after endoscopic polypectomy, 9 were histologically shown to have a residual tumor in the specimens obtained by TEM. No additional radical surgery was performed. No recurrence was noted during the median of 3 years’ follow-up.

CONCLUSION: Full-thickness excision using TEM could be a first surgical option for complete removal of upper small rectal neuroendocrine tumors.

Circumferential submucosal incision prior to endoscopic mucosal resection provides comparable clinical outcomes to submucosal dissection for well-differentiated neuroendocrine tumors of the rectum

BACKGROUND

Small rectal neuroendocrine tumors (NETs) can be treated with endoscopic resection. Endoscopic submucosal dissection (ESD) has been accepted as a reliable technique, but it is difficult. We evaluated the feasibility and efficacy of precut and endoscopic mucosal resection (CSI-EMR) for rectal NETs compared to ESD.

METHODS

Patients with rectal NETs were enrolled consecutively. ESD or CSI-EMR was performed at operator's discretion. Histological and clinical outcomes were measured and compared between the two treatment modalities.

RESULTS

Thirty-three patients were enrolled in the study. Seventeen NETs were treated by the ESD method and 16 were treated by CSI-EMR. Both groups had similar mean tumor diameters (ESD 7.53 ± 1.94 vs. CSI-EMR 6.63 ± 1.99 mm; p = 0.197). En bloc resection was achieved in 100 % of ESD group and 87.5 % of CSI-EMR group. Lateral margin involvement occurred in one patient in ESD group and two in CSI-EMR group. The histologically complete resection rate was 88.2 % (15 of 17) in the ESD group and 81.2 % (13 of 16) in CSI-EMR group (p = 0.592). One case of perforation occurred in both groups. Delayed bleeding did not occur. None of the measured outcomes were different between the two groups. Operating time was significant shorter in CSI-EMR group than in ESD group (9.69 vs. 20.12 min, respectively; p value = 0.004).

CONCLUSIONS

CSI-EMR results in reliable clinical outcomes for small rectal NETs comparable to those of ESD. CSI-EMR is technically feasible and more time saving.

Natural course of an untreated metastatic perirectal lymph node after the endoscopic resection of a rectal neuroendocrine tumor

Lymph node metastasis is rare in small (i.e., <10 mm) rectal neuroendocrine tumors (NETs). In addition to tumor size, pathological features such as the mitotic or Ki-67 proliferation index are associated with lymph node metastasis in rectal NETs. We recently treated a patient who underwent endoscopic treatment of a small, grade 1 rectal NET that recurred in the form of perirectal lymph node metastasis 7 years later. A 7-mm-sized perirectal lymph node was noted at the time of the initial endoscopic treatment. The same lymph node was found to be slightly enlarged on follow-up and finally confirmed as a metastatic NET. Therefore, the perirectal lymph node metastasis might have been present at the time of the initial diagnosis. However, the growth rate of the lymph node was extremely low, and it took 7 years to increase in size from 7 to 10 mm. NETs with low Ki-67 proliferation index and without mitotic activity may grow extremely slowly even if they are metastatic.

Ligation-assisted endoscopic enucleation for the treatment of colorectal submucosal tumours originating in the muscularis propria

AIM

A ligation-assisted endoscopic enucleation (EE-L) technique was developed and was evaluated to determine its efficacy and safety for treating colorectal submucosal tumours (< 10 mm) originating in the muscularis propria.

METHOD

EE-L was used to treat 13 patients between January 2011 and January 2014. The tumour was sucked into a transparent cap and ligated at its base by a rubber band ligature attached to the tip of the endoscope. With the creation of a pseudo-stalk, the tumour was then enucleated using endoscopic dissection and the wound was closed with clips.

RESULTS

All tumours [median diameter 6.8 (4-10) mm] were successfully enucleated [procedure time 19 (11-27) min]. Histopathological examination identified 11 (84.6%) to be leiomyoma and 2 (15.4%) low-risk gastrointestinal stromal tumours. No perforations or massive haemorrhage occurred and there were no recurrences during a follow-up of 3-39 months.

CONCLUSION

EE-L is a successful technique for the removal of small colorectal tumours in the muscularis propria with few complications and enables a histopathological diagnosis. In this study, all the resected lesions had a benign pathology.

Endoscopic submucosal dissection for the treatment of rectal carcinoid tumors 7-16 mm in diameter

OBJECTIVE

Small rectal carcinoid tumors (<10 mm) are often removed via endoscopic submucosal dissection (ESD). However, the use of ESD for tumors of an intermediate size (7-16 mm) is less well documented. This study aimed to evaluate the efficacy and safety of ESD compared with endoscopic mucosal resection using a cap (EMR-C) for the treatment of 7-16-mm rectal carcinoids.

MATERIAL AND METHODS

From September 2007 to August 2012, 55 patients with large rectal carcinoid tumors were treated by EMR-C (30 cases) or ESD (25 cases). The en bloc resection rate, pathological complete response (pCR) rate, procedure time, and incidence rates of complications, local recurrence, and distant metastasis were evaluated.

RESULTS

The basic and clinical characteristics of the patients in the two groups did not differ significantly (p > 0.05). The mean procedure time was longer for ESD than EMR-C (24.79 ± 4.89 vs. 9.52 ± 2.14 min, p < 0.001). The rates of en bloc resection and pCR were higher with ESD than with EMR-C (100 vs. 83.33 %, and 100 vs. 70.00 %, respectively). No patients in the EMR-C group experienced complications. However, in the ESD group, two cases of perforation occurred, and one patient experienced delayed bleeding. These complications were successfully managed via endoscopical therapy. Five cases of local recurrence were detected after EMR-C, whereas no patients experienced recurrence after ESD.

CONCLUSIONS

Compared with EMR-C, ESD appears to be a more favorable therapeutic option for the treatment of rectal carcinoid tumors less than 16 mm in diameter based on improved rates of pCR and local recurrence.

Resection of multiple rectal carcinoids with transanal endoscopic microsurgery: Case report

Multiple rectal carcinoids are rare. Due to the unreliability of endoscopic polypectomy in treating these submucosal lesions, a laparotomy is usually performed. We present a case report on multiple rectal carcinoids with three carcinoid foci < 10 mm in diameter located in the mid-rectum. Preoperative examination showed the lesions to be confined to the submucosal layer with no perirectal nodal involvement. A transanal endoscopic microsurgery was successfully performed to remove the three lesions with accurate full-thickness resection followed by secured suture closure. The postoperative pathology revealed neuroendocrine tumors G1 (carcinoids) located within the submucosal layer without lymphatic or vessel infiltration. Both the deep and lateral surgical margins were completely free of tumor cells. The patient recovered quickly and uneventfully. No tumor recurrence was observed at the six-month follow-up. For the multiple small rectal carcinoids without muscularis propria or lymphatic invasion, transanal endoscopic microsurgery offers a reliable and efficient alternative approach to traditional laparotomy for select patients, with the added advantages of minimally invasive surgery.