Rectal carcinoids

Effective utilization of polypectomy in endoscopic salvage treatment of rectal neuroendocrine tumors: a retrospective cohort study

Purpose

Current guidelines recommend endoscopic resection for rectal neuroendocrine tumors (RNETs) under 10 mm. Incomplete resections necessitate salvage procedures, highlighting the need for complete R0 resection. This study evaluates the efficacy and safety of wide hot snare polypectomy (WHSP) compared to endoscopic submucosal dissection (ESD) and endoscopic mucosal resection (EMR) for the salvage treatment of small RNETs.

Methods

This retrospective study was conducted at Korea University Guro Hospital from January 2018 to December 2022. It compared the outcomes of salvage resections for RNETs ≤10 mm using 2 approaches: ESD and EMR vs. WHSP. Demographics, tumor characteristics, and clinical outcomes were compared. Efficacy was evaluated by the histological complete resection rate and procedure time, while safety was assessed by the incidence of complications.

Results

Out of 135 patients undergoing salvage resection for RNET, 14 who underwent transanal excision were excluded. Of the remaining 121, 99 underwent EMR or ESD, and 22 underwent WHSP. Baseline characteristics were similar between the 2 groups. The WHSP group demonstrated a significantly higher R0 resection rate (72.7% vs. 49.5%, P = 0.010) and a shorter median procedure time (3.5 minutes vs. 8.3 minutes). No complications were reported in the WHSP group.

Conclusion

WHSP is a rapid, straightforward, safe, and effective approach for the salvage treatment of RNETs less than 10 mm in diameter, particularly in patients without additional risk factors.

A Comprehensive Review on Neuroendocrine Neoplasms: Presentation, Pathophysiology and Management

Neuroendocrine neoplasms (NENs) are a group of heterogeneous tumors with neuroendocrine differentiation that can arise from any organ. They account for 2% of all malignancies in the United States. A significant proportion of NEN patients experience endocrine imbalances consequent to increased amine or peptide hormone secretion, impacting their quality of life and prognosis. Over the last decade, pathologic categorization, diagnostic techniques and therapeutic choices for NENs-both well-differentiated neuroendocrine tumors (NETs) and poorly differentiated neuroendocrine carcinomas (NECs)-have appreciably evolved. Diagnosis of NEN mostly follows a suspicion from clinical features or incidental imaging findings. Hormonal or non-hormonal biomarkers (like serum serotonin, urine 5-HIAA, gastrin and VIP) and histology of a suspected NEN is, therefore, critical for both confirmation of the diagnosis and classification as an NET or NEC. Therapy for NENs has progressed recently based on a better molecular understanding, including the involvement of mTOR, VEGF and peptide receptor radionuclide therapy (PRRT), which add to the growing evidence supporting the possibility of treatment beyond complete resection. As the incidence of NENs is on the rise in the United States and several other countries, physicians are more likely to see these cases, and their better understanding may support earlier diagnosis and tailoring treatment to the patient. We have compiled clinically significant evidence for NENs, including relevant changes to clinical practice that have greatly updated our diagnostic and therapeutic approach for NEN patients.

The genetic alterations of rectal neuroendocrine tumor and indications for therapy and prognosis: a systematic review

Neuroendocrine tumors (NETs) are a type of rare tumor that can occur at multiple organs. Rectal NETs are the most common NETs in gastrointestinal tract. Due to the rarity of rectal NETs in rectal cancer, the molecular features and the correlation with patient therapeutic response and prognosis have not been investigated in detail. In this review, we focused on the molecular features, potential therapeutic targets and prognosis of rectal NETs. By summarizing the relevant studies, we established the mutational landscape of rectal NETs and identified a series of large fragment variations. Driver genes including TP53, APC, KRAS, BRAF, RB1, CDKN2A and PTEN were found as the top mutated genes. Large fragment alterations mainly involved known driver genes, including APC, TP53, CCNE1, MYC, TERT, RB1 and ATM. Germline mutations of APC, MUTYH, MSH6, MLH1 and MSH2 associated with Lynch syndrome or FAP were also found in rectal NETs. The BRAF-V600E mutation was reported as an actionable target in rectal NETs, and the combined BRAF/MEK inhibitors were found to be effective targeting BRAF-V600E in advanced or metastatic NETs. The known prognostic risk factors of rectal adenocarcinoma, including a series of demographic and clinicopathological factors were also prognostic factors for rectal NETs. Furthermore, three types of markers, including genetic alterations, protein expression levels and methylation, were also suggested as prognostic factors for rectal NETs. In summary, we established the landscape of mutations and large-fragment alterations of rectal NETs, and identified potential therapeutic targets and a series of prognostic factors. Future studies may focus on the optimization of therapeutic strategies based on potential actionable biomarkers.

Survival in patients with neuroendocrine tumors of the colon, rectum and small intestine

BACKGROUND

Neuroendocrine neoplasms (NENs) of the colon, rectum and small intestine (SI) are increasing in incidence and prevalence. We evaluated the 5-year overall survival (OS), and cancer-specific survival (CSS).

METHODS

The Surveillance, Epidemiology, and End Results (SEER) 18 registry from 2000 to 2017 was accessed to identify patients with colonic, rectal, and SI NENs.

RESULTS

46,665 patients were diagnosed with NENs of the colon (n = 10,518, 22.5%), rectum (18,063, 38.7%), and SI (18,084, 38.8%). By tumor site alone, patients with well-differentiated neuroendocrine tumors (NETs) of the rectum had improved 5-year OS (HR 0.72, 95% CI 0.68-0.77, p < 0.001). However, patients with rectal poorly-differentiated neuroendocrine carcinomas (NECs) who underwent oncologic resection had lower 5-year OS (35.1%) compared to colon (41.9%), and SI (72.5%).

CONCLUSIONS

Surgical resection may improve 5-year OS for NECs of the SI and colon, except in the rectum where survival was reduced. More frequent surveillance and timely initiation of systemic therapy should be considered for rectal NECs.

Diagnostic performance and impact on patient management of [68Ga]Ga-DOTA-TOC PET/CT in colorectal neuroendocrine tumors derived from hindgut

The main purpose of this retrospective study was to determine the diagnostic performance of [68Ga]Ga-DOTA-D-Phe1-Try3-octreotide(DOTA-TOC) positron emission tomography/computed tomography (PET/CT) in patients with well-differentiated colorectal Neuroendocrine Tumours (NETs) originating from the hindgut. The other aims were to assess the impact of the examination on patient management and to analyze the results of 2-[18F]FDG and/or 6-[18F]FDOPA PET/CT when they were performed. [68Ga]Ga-DOTA-TOC PET/CT and clinical data from 30 patients with biopsy-proven well-differentiated NETs originating from the hindgut were retrospectively reviewed and analyzed by comparing the [68Ga]Ga-DOTA-TOC PET/CT findings with pathological and/or follow-up data. We also compared the [68Ga]Ga-DOTA-TOC PET/CT results with 2-[18F]FDG and/or 6-[18F]FDOPA PET/CT results in 6 patients. The impact on management was determined in hindsight by comparing the patient management decided before and after the TEP examination based on data from multidisciplinary team meetings. On a patient basis, [68Ga]Ga-DOTA-TOC PET/CT was accurate in 30 of the 30 examinations. [68Ga]Ga-DOTA-TOC PET/CT correctly identified the primary tumor in all patients with primary tumors not resected before the examination and allowed the detection of unexpected distant metastases in 36% of the patients referred for initial staging. [68Ga]Ga-DOTA-TOC PET/CT findings affected patient management in 57% of cases with generally major intermodality changes. Intraindividual comparison of the results of the different PET radiopharmaceuticals showed a clear superiority of [68Ga]Ga-DOTA-TOC PET/CT considering both the number of lesions and the intensity of uptake. [68Ga]Ga-DOTA-TOC PET/CT is an accurate imaging modality for the assessment of well-differentiated colorectal NETs that highly impact patient management. Thus, we suggest that [68Ga]Ga-DOTA-TOC PET/CT be employed as a first choice for the assessment of these tumors in nuclear medicine.

Epidemiological, clinical and endoscopic characteristics of colorectal neuroendocrine neoplasms: a population-based study in the Netherlands

Background and study aims  Neuroendocrine neoplasms (NEN) account for a small number of colorectal neoplasms. Endoscopic detection is essential for diagnosis, treatment and follow-up. Little is known about incidence of NENs in colonoscopy populations or the relationship between clinical, endoscopic and histopathologic features. We evaluated epidemiology, endoscopic and clinical characteristics of colorectal NENs in a population-based cohort. Patients and methods  Medical records of NEN cases were cross-linked with the national pathology database from January 2001 to December 2015, in South Limburg County, the Netherlands, covering four endoscopy units. Senior pathologists reviewed and classified NENs using World Health Organization 5th edition (2019) guidelines. Results  The number of colorectal NEN diagnoses was stable over time with 0.6 NEN per 1,000 patients. A total of NENs were detected in 85 patients: 65 neuroendocrine tumors (NETs) and 20 poorly differentiated neuroendocrine carcinomas (NECs). Rectal NETs were usually small sessile/submucosal lesions with yellowish (lipoma-like) color. Colonic NETs were larger sessile/submucosal lesions with darker color compared to background. Colorectal NECs presented as large, dark-colored lesions with ulcerated/necrotizing areas. Conclusions  Our population-based data point to a stable and low incidence of 0.6 NEN per 1,000 patients in the Netherlands. Rectal NETs mainly present as small sessile yellowish lesions. Colonic NETs present as larger and darker lesions than background mucosa and NECs as darker lesions than background with ulceration/necrosis. Standardized endoscopic characterization of colorectal NENs is necessary to improve recognition of these lesions and provide a basis for evidence-based treatment and surveillance recommendations.

Endoscopic treatment for rectal neuroendocrine tumor: which method is better?

Recently, research on rectal neuroendocrine tumors (NETs) has increased during the last few decades. Rectal NETs measuring <10 mm without atypical features and confined to the submucosal layer have only 1% risk of metastasis, and the long-term survival probability of patients without metastasis at the time of diagnosis is approximately 100%. Therefore, the current guidelines suggest endoscopic resection of rectal NETs of <10 mm is regarded as a safe therapeutic option. However, there are currently no clear recommendations for technique selection for endoscopic resection. The choice of treatment modality for rectal NETs should be based on the lesion size, endoscopic characteristics, grade of differentiation, depth of vertical involvement, lymphovascular invasion, and risk of metastasis. Moreover, the complete resection rate, complications, and experience at the center should be considered. Modified endoscopic mucosal resection is the most suitable resection method for rectal NETs of <10 mm, because it is an effective and safe technique that is relatively simple and less time-consuming compared with endoscopic submucosal dissection. Endoscopic submucosal dissection should be considered when the tumor size is >10 mm, suctioning is not possible due to fibrosis in the lesion, or when the snaring for modified endoscopic mucosal resection does not work well.

Diagnosis and Management of Rectal Neuroendocrine Tumors (NETs)

Rectal neuroendocrine tumors (NETs) are rare, with an incidence of 0.17%, but they represent 12% to 27% of all NETs and 20% of gastrointestinal NETs. Although rectal NETs are uncommon tumors, their incidence has increased over the past few years, and this is probably due to the improvement in detection rates made by advanced endoscopic procedures. The biological behavior of rectal NETs may be different: factors predicting the risk of metastases have been identified, such as size and grade of differentiation. The tendency for metastatic diffusion generally depends on the tumor size, muscular and lymphovascular infiltration, and histopathological differentiation. According to the current European Neuroendocrine Tumor Society (ENETS) guidelines, tumors that are smaller than 10 mm and well differentiated are thought to have a low risk of lymphovascular invasion, and they should be completely removed endoscopically. Rectal NETs larger than 20 mm have a higher risk of involvement of muscularis propria and high metastatic risk and are candidates for surgical resection. There is controversy over rectal NETs of intermediate size, 10–19 mm, where the metastatic risk is considered to be 10–15%: assessment of tumors endoscopically and by endoanal ultrasound should guide treatment in these cases towards endoscopic, transanal, or surgical resection.

Clinical and pathological characteristics and prognosis of 132 cases of rectal neuroendocrine tumors

BACKGROUND

Neuroendocrine tumors (NETs) frequently occur in the gastrointestinal tract, lung, and pancreas, and the rectum and appendix are the sites with the highest incidence. Epidemiology statistics show that an estimated 8000 people every year in the United States are diagnosed with NETs occurring in the gastrointestinal tract, including the stomach, intestine, appendix, colon, and rectum. The pathological changes and clinical symptoms of NETs are not specific, and therefore they are frequently misdiagnosed.

AIM

To investigate the clinical symptoms, pathological characteristics, treatment, and prognosis of rectal neuroendocrine tumors (RNETs) by analyzing the clinical and pathological data of 132 RNET cases at our hospital.

METHODS

All RNETs were graded according to Ki-67 positivity and mitotic events. The tumors were staged as clinical stages I, II, III, and IV according to infiltrative depth and tumor size. COX proportional hazard model was used to assess the main risk factors for survival.

RESULTS

These 132 RNETs included 83 cases of G1, 21 cases of G2, and 28 cases of G3 (neuroendocrine carcinoma) disease. Immunohistochemical staining showed that 89.4% of RNETs were positive for synaptophysin and 39.4% positive for chromogranin A. There were 19, 85, 23, and 5 cases of clinical stages I, II, III, and IV, respectively. The median patient age was 52.96 years. The diameter of tumor, depth of invasion, and pathological grade were the main reference factors for the treatment of RNETs. The survival rates at 6, 12, 36, and 60 mo after operation were 98.5%, 94.6%, 90.2%, and 85.6%, respectively. Gender, tumor size, tumor grade, lymph node or distant organ metastasis, and radical resection were the main factors associated with prognosis of RNETs. Multivariate analysis showed that tumor size and grade were independent prognostic factors.

CONCLUSION

The clinical symptoms of RNETs are not specific, and they are easy to misdiagnose. Surgery is the main treatment method. The grade and stage of RNETs are the main indices to evaluate prognosis.

Synchronous NET and colorectal cancer development: a case report

Background

The incidence of synchronous gastrointestinal neuroendocrine tumors (GI-NETs) and colorectal cancer is very low.

Case presentation

We present a 72-year-old man diagnosed with a rectal neuroendocrine tumor (NET) with multiple organ metastases and simultaneous sigmoid colon cancer. Although the NET was his prognostic factor, he underwent a laparoscopic sigmoidectomy at first because it was expected that the colon cancer would cause obstruction or bleeding during NET treatment. Subsequently, he started taking everolimus.

Conclusions

We should consider surgical resection of the synchronous cancer before systemic therapy for a GI-NET regardless of the difference in prognosis between synchronous tumors, if the cancer may impair the continuation of systemic therapy.

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.

How should incidental NEN of the pancreas and gastrointestinal tract be followed?

Neuroendocrine gastro-entero-pancreatic neoplasms (GEP-NENs) constitute a heterogeneous group of tumors, whose incidence has increased over the years. The most frequent site for primary disease is the stomach followed by small and large intestine, and pancreas. In the last decade, a dramatic growing in the incidence of small, incidental GEP-NENs has been recorded. In parallel, an increasing attitude toward more conservative approaches instead of surgical management has being widely spreading. This is particularly true for small, asymptomatic, pancreatic NEN as for these tumor forms an active surveillance has proven to be safe and feasible. Primary site and biological features of the neoplasms lead to different strategies and indications for surveillance and follow-up. This review focuses on the current evidence on modality and timing of surveillance and conservative treatment of incidentally discovered lesions.

Predictive Factors for Lymph Node Metastasis and Prognostic Factors for Survival in Rectal Neuroendocrine Tumors

INTRODUCTION

Neuroendocrine tumors have malignant potential, and lymph node metastasis can occur. This study aimed to identify predictive factors of lymph node metastasis and prognostic factors for survival in rectal neuroendocrine tumors.

METHODS

Sixty-four patients underwent endoscopic or surgical treatment for rectal NET. The data on these patients were collected in our database prospectively and reviewed retrospectively.

RESULTS

Transanal excision was performed in 28 (43.8%) patients, endoscopic mucosal resection or submucosal dissection was performed in 15 (23.4%) patients, and radical resection was performed in 21 (31.8%) patients. Lymph node and distant metastasis was present in 16 (25.0%) and fir (7.8%) patients. The significant risk factors for lymph node metastasis identified in the multivariable analyses were tumor size (≥ 2 cm, p = 0.003) and tumor grade (G2, p < 0.001; G3, p = 0.008). In patients with a tumor smaller than 2 cm, the risk factors for lymph node metastasis included the tumor grade, mitosis count, and Ki-67 index. The median follow-up period was 30.0 months, and recurrence developed in four (6.8%) patients. The significant prognostic factors for survival included tumor size, T stage, lymph node metastasis, and tumor grade.

CONCLUSION

Tumor grade combined with tumor size is an important predictive factor for lymph node metastasis and could serve as a prognostic factor for survival outcomes.

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.

Well-Differentiated Neuroendocrine Tumor-A Low b-Grade Tumor's Aggressive Course and Dismal Outcome: A Case Report

INTRODUCTION

Incidence of well-differentiated neuroendocrine tumors (NETs) of the colon and rectum is increasing and is now approximately 1 per 100,000 in the US. NETs are either well-differentiated (indolent) or poorly differentiated (aggressive). The majority of these tumors are found incidentally during screening colonoscopies and rarely are associated with symptoms of hormonal syndrome, even during the advanced stage. Metastatic well-differentiated NETs of the colon and rectum are incurable, hard to treat, and associated with a poor prognosis and survival rates similar to colorectal adenocarcinoma survival.

CASE PRESENTATION

A 56-year-old man presented to our clinic with right-sided weakness and a 40-pound weight loss during the previous 2 months. A neurologic examination was remarkable for atrophy of the right trapezius muscle and decreased strength in the right upper extremity. Imaging revealed extensive blastic and lytic lesions involving the axial skeleton, a large rectal mass, a large necrotic nodal mass extending from the left iliac region to the level of the left renal veins, and multiple necrotic liver metastasis. Liver lesion fine-needle aspiration findings were consistent with metastatic well-differentiated neuroendocrine carcinoma.

DISCUSSION

This case illustrates how a low-grade tumor can have an aggressive course with poor outcomes. Metastatic well-differentiated NETs of the colon and rectum remain difficult to treat because evidence is scarce. More research is needed on this topic.

Rectal Neuroendocrine Tumor G1 with a Solitary Hepatic Metastatic Lesion

Rectal neuroendocrine tumor (NET) is a relatively rare tumor. NET is classified as G1, G2, or G3 according to the degree of mitosis or Ki-67 proliferation index, which reflect the malignant potential of the tumor, such as metastasis. Advanced cases with metastasis are indicated for chemotherapy treatment. However, the efficacy of chemotherapy is limited. Therefore, resection is considered, even in metastatic cases, if complete resection is possible. We herein report a case of small rectal NET discovered with hepatic metastasis classified as G1. The patient showed good progress with no recurrence after undergoing hepatectomy and endoscopic resection of rectal NET.

Metastatic rectal neuroendocrine tumor presenting as an inguinal mass: A case report and review of literature

•

Neuroendocrine tumors (NETs) are a heterogeneous and relatively rare group of neoplasms that often develop along the gastrointestinal tract.

•

Rectal NETs are usually incidental findings on colonoscopy or present with metastatic disease.

•

Treatment regimens for advanced metastatic rectal NETs are currently being developed.

Introduction

Neuroendocrine tumors (NET) are a heterogeneous group of rare carcinomas that most often manifest along the gastrointestinal tract. Some of these tumors have the ability to secrete vasoactive peptides and hormones.

Presentation of case

The present report describes the case of a previously healthy 52-year old man who presented with a painful right inguinal mass. Upon surgical exploration, a lymph node metastasis of a high-grade NET was found. Further investigations revealed a rectal NET with pulmonary, pelvic and penile metastases.

The patient was treated with 6 cycles of carboplatin and etoposide. Although initial follow-up imaging after 3 cycles of chemotherapy revealed stable disease, there was progression of the metastases after completion of systemic treatment. Second and third-line chemotherapy regimens were instituted along with pelvic and whole-brain radiation therapy extending the patient’s survival to 18 months after the initial diagnosis.

Discussion

This case highlights the aggressive nature high-grade NETs as described in the current literature. Treatment modalities of colorectal NETs include local excision for non-metastatic disease and systemic palliative chemotherapy for advanced disease. However, there are no controlled trials in favor of palliative chemotherapy.

Conclusion

Rectal NETs are rare tumors which often have an atypical presentation or present in advanced stages. Currently, surgical options exist for local disease while treatment modalities for more advanced disease is still under investigation.

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.

Nonlinear optical microscopy for label-free detection of gastrointestinal neuroendocrine tumors

Neuroendocrine tumors (NETs), which are rare and slow-growing neoplasms, pose a diagnostic challenge as they are clinically silent at the time of presentation. Here, gastrointestinal neuroendocrine tumors were researched by nonlinear microscopy, and results demonstrate that this technique has the capability to identify neuroendocrine tumors in the absence of labels and can, in particular, detect rare neuroendocrine tumor cells, vascular invasion, desmoplastic reaction, and fibroelastosis induced by neuroendocrine tumors. These conclusions highlight the possibility of nonlinear optical microscopy as a diagnostic tool for label-freely differentiating neuroendocrine tumors by these histopathologic features.

The Clinicopathologic Features and Treatment of 607 Hindgut Neuroendocrine Tumor (NET) Patients at a Single Institution

The clinicopathologic features of hindgut neuroendocrine tumor (NET) as well as the treatment outcomes are not well known. There are currently no published data on treatment outcomes for patients with metastatic hindgut NET. The aim of this study was to conduct a comprehensive analysis of clinicopathologic features, treatments and survival in hindgut NET patients. Among patients who were pathologically diagnosed with hindgut NET at Samsung Medical Center between March 2001 and February 2015, 607 were analyzed in this study. Hindgut NETs were defined as NETs that originated from the transverse and distal colon, rectum, and anus. Primary sites included 81 colon (13.3%) and 526 rectum (86.7%). According to the WHO classification, 578 patients (95.2%) had grade 1 NETs, 17 (2.8%) grade 2 NETs, and 12 (2.0%) had neuroendocrine carcinoma (NEC). Forty-two patients (6.9%) had extensive disease, while the majority (93.1%, 565 patients) only exhibited localized disease. The 5- and 10-year survival rates of 565 localized NET patients were 98.1% and 95.3%, respectively. The median OS in 42 patients with extensive disease was 24.8 months (95% CI, 10.7-38.8). Among 565 patients with localized disease, the majority (484 patients, 85.7%) were treated with endoscopic procedure by gastroenterologists. For 42 patients with extensive disease, 17 patients were managed by supportive care, 3 by concurrent chemoradiotherapy (CCRT), and 22 by systemic therapy. Among these 22 patients, 12 patients received only first-line therapy, 8 had second-line, and only 2 patients had third-line therapy. As first-line chemotherapy, the most commonly used regimens were etoposide plus cisplatin (N = 7) and long acting octreotide (N = 7). During treatment courses, the most commonly used regimen was long-acting octreotide. The median OS in 22 metastatic NET patients receiving systemic therapy was 19.3 months (95% CI, 3.2-35.3). Multivariate analysis in all 607 hindgut NETs patients suggested that the extent and the primary site of disease were significant independent prognostic factors for long term survival. This analysis provides useful information about the clinicopathologic features, treatments and survival outcomes for hindgut NET patients.

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.

Diagnostic accuracy of endoscopic ultrasonography for rectal neuroendocrine neoplasms

AIM: To investigate the diagnostic accuracy of endoscopic ultrasonography (EUS) for rectal neuroendocrine neoplasms (NENs) and the differential diagnosis of rectal NENs from other subepithelial lesions (SELs).

METHODS: The study group consisted of 36 consecutive patients with rectal NENs histopathologically diagnosed using biopsy and/or resected specimens. The control group consisted of 31 patients with homochronous rectal non-NEN SELs confirmed by pathology. Epithelial lesions such as cancer and adenoma were excluded from this study. One EUS expert blinded to the histological results reviewed the ultrasonic images. The size, original layer, echoic intensity and homogeneity of the lesions and the perifocal structures were investigated. The single EUS diagnosis recorded by the EUS expert was compared with the histological results.

RESULTS: All NENs were located at the rectum 2-10 cm from the anus and appeared as nodular (n = 12), round (n = 19) or egg-shaped (n = 5) lesions with a hypoechoic (n = 7) or intermediate (n = 29) echo pattern and a distinct border. Tumors ranged in size from 2.3 to 13.7 mm, with an average size of 6.8 mm. Homogeneous echogenicity was seen in all tumors except three. Apart from three patients (stage T2 in two and stage T3 in one), the tumors were located in the second and/or third wall layer without involvement of the fourth and fifth layers. In the patients with stage T1 disease, the tumors were located in the second wall layer only in seven cases, the third wall layer only in two cases, and both the second and third wall layers in 27 cases. Approximately 94.4% (34/36) of rectal NENs were diagnosed correctly by EUS, and 74.2% (23/31) of other rectal SELs were classified correctly as non-NENs. Eight cases of other SELs were misdiagnosed as NENs, including two cases of inflammatory lesions and one case each of gastrointestinal tumor, endometriosis, metastatic tumor, lymphoma, neurilemmoma, and hemangioma. The positive predictive value of EUS for rectal NENs was 80.9% (34/42), the negative predictive value was 92.0% (23/25), and the diagnostic accuracy was 85.1%.

CONCLUSION: EUS has satisfactory diagnostic accuracy for rectal NENs with good sensitivity, but unfavorable specificity, making the differential diagnosis of NENs from other SELs challenging.

Examining rectal carcinoids in the era of screening colonoscopy: a surveillance, epidemiology, and end results analysis

BACKGROUND

Little is known about the epidemiology of rectal carcinoids in the United States since the implementation of screening colonoscopy.

OBJECTIVE

The goal of this study was to identify epidemiological differences between rectal and small intestinal carcinoids.

DESIGN

This study was retrospective in design.

SETTING

Surveillance, Epidemiology and End Results registry data from 1992 to 2008 were examined.

PATIENTS

Patients with rectal carcinoids included those with carcinoid tumors of the rectum. Patients with small intestinal carcinoids included those with carcinoids in the duodenum, jejunum, or ileum.

MAIN OUTCOME MEASURE

Epidemiological characteristics of rectal carcinoids were identified and compared with small intestinal carcinoids using multiple variable logistic regression.

RESULTS

Patients with rectal carcinoids were more likely to be women (OR, 1.196 (95% CI, 1.090-1.311); p < 0.001). Rectal carcinoids were more common among all minorities, including Asians (OR, 10.063 (95% CI, 8.330-12.157); p < 0.001), blacks (OR, 1.994 (95% CI, 1.770-2.246); p < 0.001), and Hispanics (OR, 2.682 (95% CI, 2.291-3.141), p < 0.001). Patients in the 50- to 59-year age group (OR, 0.752 (95% CI, 0.599-0.944); p = 0.014) were more likely to be diagnosed with rectal carcinoids than those in the 60- to 69-year (OR, 0.481 (95% CI, 0.383-0.605); p < 0.001) and ≥70-year age groups (OR, 0.220 (95% CI, 0.175-0.277); p < 0.001). Rectal carcinoids were more likely to be diagnosed in the screening colonoscopy era among the 50- to 59-year age group (OR, 1.432 (95% CI, 1.082-1.895); p = 0.012). Since the implementation of screening colonoscopy in 2000, the proportion of patients diagnosed with rectal carcinoids has been greater than the proportion diagnosed with small intestinal carcinoids in every year except 2001, and the proportion of patients diagnosed with rectal carcinoids after 2000 has been greater than the proportion diagnosed with small intestinal carcinoids in 12 of 13 Surveillance, Epidemiology, and End Results registry reporting agencies.

CONCLUSIONS

Rectal carcinoids and small intestinal carcinoids are epidemiologically distinct tumors with unique presentations. In the era of screening colonoscopy, rectal carcinoids are the more common tumor.

Surgery for GEP-NETs

Surgery is the only treatment that may cure the patient with gastroentero-pancreatic (GEP) neuroendocrine tumours (NET) and neuroendocrine carcinomas (NEC) and should always be considered as first line treatment if R0/R1 resection can be achieved. The surgical and interventional procedures for GEP-NET are accordingly described below. Life-long follow-up should be performed in almost all patients at a specialized NET center.

Transcatheter arterial embolization with trisacryl gelatin microspheres (Embosphere(®)) leads to life-threatening tumor lysis syndrome in a rectal carcinoid patient with hepatic metastases

The incidence of gastrointestinal carcinoids appears to be increasing, and the rectum is the third most common location. Transcatheter arterial embolization (TAE) with trisacryl gelatin microspheres (Embosphere^®) has been reported as an effective method for hepatic metastases of rectal carcinoids. Complications are uncommon and usually of minor consequence. We report an unusual case of a 34-year-old man with tumor lysis syndrome following TAE with Embosphere^® in a patient with multiple hepatic metastases of a rectal carcinoid. Early detection and effective treatment are essential for this rare but potentially catastrophic complication.

The NANETS consensus guidelines for the diagnosis and management of gastrointestinal neuroendocrine tumors (nets): well-differentiated nets of the distal colon and rectum

Neuroendocrine tumors (NETs) of the distal colon and rectum are also known as hindgut carcinoids based on their common embryologic derivation. Their annual incidence in the United States is rising, primarily as a result of increased incidental detection. Symptoms of rectal NETs include hematochezia, pain, and change in bowel habits. Most rectal NETs are small, submucosal in location, and associated with a very low malignant potential. Tumors larger than 2 cm or those invading the muscularis propria are associated with a significantly higher risk of metastatic spread. Colonic NETs proximal to the rectum are rarer and tend to behave more aggressively. The incidence of rectal NETs in African Americans and Asians is substantially higher than in Caucasians. Colorectal NETs are generally not associated with a hormonal syndrome such as flushing or diarrhea. A multidisciplinary approach is recommended in diagnosing and managing hindgut NETs.

Surgical treatment by partial petrosectomy for a middle-ear carcinoid with progressive extension: a case report and review of the literature

We herein report a 59-year-old male patient with a recurrent carcinoid tumor of the middle ear 7 years after a tympanomastoidectomy. The CT and dynamic MRI demonstrated an extensive tumor close to the carotid artery canal and the jugular bulb, and the tumor was removed by a partial petrosectomy with a transmastoid approach. The histopathological findings revealed a solid and trabecular tumor with cells positive for cytokeratin, chromogranin A, synaptophysin, and CD56. The MIB-1 antibody for the Ki-67 antigen was positive in 6.6% of the tumor cells. The relevant literature is reviewed in regard to the present case.

A proposed staging system for rectal carcinoid tumors based on an analysis of 4701 patients

BACKGROUND

The lack of a clinically relevant staging system for carcinoid tumors of the rectum creates a persistent challenge for clinicians trying to provide patients with meaningful prognostic information. The purpose of this study was to identify the clinicopathologic factors that affect survival for patients diagnosed with carcinoid of the rectum, and to use this information to create a staging system.

METHODS

A search of 15,983 patients with carcinoid tumors from the National Cancer Institute's SEER (Surveillance Epidemiology and End Results) database identified 4701 patients with rectal carcinoid tumors from 1973 to 2004. Patients were analyzed according to various clinicopathologic factors and a tumor (T1, T2, T3), lymph node (N0, N1), and metastasis (M0, M1) staging system was created according to these parameters. The staging system was developed using log rank tests and the Cox proportional hazards model.

RESULTS

Of the 4701 patients, 2329 females and 2372 males were identified with a median age of 56 years (14-94). Median size of primary tumor was 0.6 cm (0.1-25). Lymph node metastasis was found in 111 (4%), and distant metastatic disease was present in 97 (2.4%) patients. Rectal carcinoid was the only primary malignancy in 82% of patients; 17% presented with 1 additional primary malignancy, and 1% had two or more additional malignancies. Age, size, depth of invasion, lymph node involvement, and distant metastasis were significant predictors of survival. Four stages were created according to statistically significant prognostic factors: 83% of patients were classified into Stage I, 6.5% into Stage II, 2.8% into Stage III, and 7.4% into Stage IV. Five-year survival rates were 97%, 84%, 27%, and 20% for Stages I through IV, respectively.

CONCLUSION

The newly developed TNM staging system accurately discriminates prognosis for carcinoid tumors of the rectum. Size of primary tumor, depth of invasion, lymph node involvement, and distant metastasis have the greatest impact on survival. Incorporation of this staging system into clinical practice will allow better study of outcomes and development of stage-specific treatment recommendations.

Risk factors associated with neuroendocrine tumors: A U.S.-based case-control study

Carcinoids are rare neuroendocrine tumors (NETs); however, their incidence has significantly increased in the United States over the past 30 years. Little is known about the epidemiology of these cancers and their associated risk factors. We evaluated the independent effects of multiple risk factors associated with NETs arising at 5 disease sites (small intestine, stomach, lung, pancreas and rectum). We conducted a retrospective, hospital-based, case-control study involving 740 patients with histologically confirmed NETs and 924 healthy controls. Information on different risk factors was collected, and unconditional logistic regression analysis was used to determine adjusted odds ratios (AORs) and 95% confidence interval (CI) by the maximum-likelihood method. Smoking and alcohol consumption were not associated with NETs development in either men or women. However, a family history of cancer was a significant risk factor for all NETs. A long-term history of diabetes mellitus was a significant risk factor for gastric NETs (AOR = 5.6; 95% CI, 2.1-14.5), particularly in women (AOR = 8.4; 95% CI, 1.9-38.1). Diabetes modified the risk among women with a positive family history of cancer for the development of gastric NETs (AOR = 52.2; 95% CI, 5.5-491.5). Our results suggest that the risk of NETs may mostly explained by genetic factors. The increased risk of gastric NETs in women with both diabetes and a positive family history of cancer suggest that women may have a greater genetic susceptibility to NETs than men.

Atypical endoscopic features can be associated with metastasis in rectal carcinoid tumors

BACKGROUND

Endoscopically, rectal carcinoids have a variety of sizes and features which may assist in determining treatment plans. The present study was performed to assess the relationship between endoscopic features and metastasis in rectal carcinoids.

METHODS

A total of 115 rectal carcinoids of 112 patients with rectal carcinoids were enrolled, and the medical records were retrospectively reviewed. All tumors were classified according to size (longest diameter), and then according to endoscopic features such as shape, color, and surface changes including depressions, erosion, and ulceration. The relationship between endoscopic features and metastasis was evaluated.

RESULTS

11 cases (9.6%) of the 115 rectal carcinoids presented with metastatic disease. Tumor size was associated with metastasis (p < 0.001). Endoscopic features associated with metastasis were tumor shape, surface change, and color (p < 0.001). Atypical endoscopic features occurred more frequently as the size of the tumor increased (p < 0.001). For tumors 10-19 mm in diameter, atypical surface change was associated with metastasis (p = 0.007).

CONCLUSIONS

Endoscopic features were found to be associated with metastasis in rectal carcinoids. In particular, atypical surface change may be useful in determining treatment plans for tumors 10-19 mm in diameter.

Imaging of neuroendocrine tumours (CT/MR/US)

Neuroendocrine tumours may be broadly divided into pancreatic endocrine tumours (PETs) and carcinoid neuroendocrine tumours (NETs). In both cases, patients may present with a clinical syndrome related to hormone secretion by the tumour. In these cases, cross-sectional imaging plays an important role in the localization of the primary tumour, the detection of metastases, and the assessment of response to treatment. Computed tomography (CT) is established as the primary modality, although following technological advances detection rates on magnetic resonance imaging (MRI) are now challenging those of CT. Endoscopic ultrasound has an important role in the preoperative assessment of the pancreas where a small functioning tumour or the possibility of multiple tumours is suspected. The sensitivity for the detection of small functioning tumours depends upon optimal technique, whichever modality is used. Non-functioning tumours frequently present late with mass effect, as there is no accompanying clinical syndrome. Carcinoid neuroendocrine tumours are most frequently localized on CT. MRI is usually used as a problem-solving tool. As technology evolves, detection rates may continue to improve, and the highest sensitivities may be achieved by a combination of different modalities.