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

Large Friable Rectal Neuroendocrine Tumor Complicated by Hemorrhagic Shock: A Rare Case Report and Review of the Literature

Rectal neuroendocrine tumors (NETs) are rare neoplasms that are usually asymptomatic and diagnosed incidentally. There are limited data on the presentation and management of high-grade poorly differentiated large friable rectal NETs. We report the first case of an 87-year-old male who presented with chronic diarrhea and subsequently had severe hematochezia complicated by hemorrhagic shock and cardiac arrest and was diagnosed with a 7-cm high-grade friable rectal NET. Our case sheds light on the need to consider NETs in cases of chronic diarrhea and on the importance of endoscopy-guided biopsy in the diagnosis and categorization, which can guide management.

Rectal neuroendocrine tumours and the role of emerging endoscopic techniques

Rectal neuroendocrine tumours represent a rare colorectal tumour with a 10 fold increased prevalence due to incidental detection in the era of colorectal screening. Patient outcomes with early diagnosis are excellent. However endoscopic recognition of this lesion is variable and misdiagnosis can result in suboptimal endoscopic resection with subsequent uncertainty in relation to optimal long-term management. Endoscopic techniques have shown particular utility in managing this under-recognized neuroendocrine tumour.

Optimising Outcomes and Surveillance Strategies of Rectal Neuroendocrine Neoplasms

Rectal neuroendocrine neoplasms are increasing in incidence, in part due to increased endoscopic procedures being performed for bowel cancer screening. Whilst most of these lesions are low-grade well-differentiated neuroendocrine tumours, they can have a varied clinical behaviour. Frequently, these lesions are incorrectly characterised at endoscopy and, therefore, incompletely excised using standard polypectomy techniques. Furthermore, some cases are not fully staged prior to or post resection. In this article we discuss the endoscopic and surgical options available to improve the likelihood of achieving an R0 resection and the staging procedures that should be used in these NETs. We also review factors that may suggest a higher risk of nodal involvement or recurrence. This information may help determine whether endoscopic or surgical resection techniques should be considered. In cases of R1 resection we discuss the management options available and the long-term surveillance options and when these should be offered to patients.

Rectal neuroendocrine neoplasms: what the radiologists should know

Neuroendocrine neoplasms of the rectum (R-NENs) are rare; however, their incidence has increased almost threefold in the last few decades. Imaging of R-NENs includes two primary categories: anatomic/morphologic imaging comprised of endoscopic ultrasound (EUS), computed tomography (CT), magnetic resonance imaging (MRI), and functional/molecular imaging comprising of planar scintigraphy, single-photon emission computed tomography (SPECT), and positron emission tomography (PET). The management depends on stage, dimension, atypical features, histological grade, and lymphovascular invasion (LVI). Low-risk local R-NENs can be resected endoscopically, and high-risk or locally advanced neoplasms can be treated with radical surgery and lymphadenectomy and/or chemoradiation. The review article focuses on imaging illustrations and discusses applications of different imaging modalities in diagnosing and managing R-NENs.

A case of a tiny neuroendocrine carcinoma in a large flat-elevated rectal tumor causing multiple liver metastases

Neuroendocrine tumors are rare malignancies comprising neuroendocrine cells widely distributed in the human body. They occur in various organs of the body, most commonly in the gastrointestinal tract and pancreas in the Japanese population. Mixed neuroendocrine-non-neuroendocrine neoplasm is included in the 2019 WHO classification and defined as having more than 30% of both neuroendocrine and non-neuroendocrine tumor components. However, the number of reports on mixed neuroendocrine and non-neuroendocrine tumors is particularly small. Herein, we encountered a rare case of a tiny neuroendocrine carcinoma in a large flat-elevated rectal tumor resulting in rapid multiple liver metastases. This case was referred to our institution for endoscopic submucosal dissection. Histopathological analysis showed that tubular adenocarcinoma and adenoma were the predominant lesions. Moreover, the neuroendocrine carcinoma component was less than 3% of the total tumor, measuring approximately 5 mm. However, the neuroendocrine carcinoma component was found to be the most advanced part of the infiltrate (T1b at least; SM3.8 mm). Repeat computed tomography 1 week after endoscopic submucosal dissection for evaluating intraoperative perforation revealed liver metastasis, and chemotherapy is currently underway.

Ampullary Large-Cell Neuroendocrine Carcinoma, a Diagnostic Challenge of a Rare Aggressive Neoplasm: A Case Report and Literature Review

Ampullary large-cell neuroendocrine carcinomas (LCNECs) are extremely rare, and available data are limited on case reports. They present with jaundice, non-specific abdominal pain, or weight loss, imitating adenocarcinoma. Their incidence increases due to the improved diagnostic techniques. However, preoperative diagnosis remains challenging. We report the case of a 70-year-old man with a history of metabolic syndrome, cholecystectomy, and right hemicolectomy, presenting with jaundice. Laboratory results showed increased liver biochemistry indicators and elevated CA 19-9. Esophagogastroduodenoscopy revealed an ulcerative tumor on the ampulla of Vater, and the biopsy revealed neuroendocrine carcinoma. Although computed tomography (CT) detected enlarged regional lymph nodes, the positron emission tomography (PET) showed a hyperactive lesion only in this area. Pylorus-preserving pancreatoduodenectomy with R0 resection was performed. Pathologic evaluation of the 3.1 × 1.9 cm tumor revealed an LCNEC with immunohistochemical positivity at Synaptophysin, EMA, CD56, and cytokeratin CK8/18. The Ki-67 index was 45%. Two out of the nine dissected lymph nodes were occupied by the neoplasm. The patient was discharged home free of symptoms, and adjuvant chemotherapy with carboplatin + etoposide was initiated. A comprehensive review of the reported cases showed that the preoperative biopsy result was different from the final diagnosis in few cases, regarding the subtypes. Conventional radiology cannot identify small masses, and other methods, such as endoscopy, magnetic resonance cholangiopancreatography (MRCP), and FDG-PET scan, might aid the diagnosis. Diagnosis is based on histology and immunohistochemical markers of the surgical specimens. The treatment of choice is pancreatoduodenectomy, followed by adjuvant chemotherapy. However, recurrence is frequent, and the prognosis remains poor.

State of the Art in Endoscopic Therapy for the Management of Gastroenteropancreatic Neuroendocrine Tumors

OPINION STATEMENT

Gastroenteropancreatic neuroendocrine neoplasms (GEP NENs) comprise a heterogeneous group of slow growing tumors arising from the neuroendocrine cells of the gastrointestinal (GI) tract. Although they are considered relatively rare, their incidence is rising and it is believed that the more frequent use of endoscopy and imaging studies have at least in part contributed to the increased diagnosis especially of localized neoplasms. The management of these neoplasms should be guided by a multidisciplinary NEN team following appropriate staging investigations. Localized neoplasms of the GI tract may be suitable for endoscopic therapy, while patients with pancreatic NENs, unsuitable for surgery, should be considered for endoscopic ultrasound (EUS)-guided ablation. In this review, we discuss the evidence regarding endoscopic resection of luminal NENs and EUS-guided therapy of pancreatic NENs. The efficacy, safety, and other longer-term outcomes of these techniques are summarized. In conclusion, this review of endoscopic therapies for localized NENs may be a useful guide for NEN clinicians and endoscopists who are considering these therapeutic options for the management of focal GEP NENs.

Assessment of the Risk of Nodal Involvement in Rectal Neuroendocrine Neoplasms: The NOVARA Score, a Multicentre Retrospective Study

Rectal neuroendocrine tumors (r-NETs) are rare tumors with overall good prognosis after complete resection. However, there is no consensus on the extension of lymphadenectomy or regarding contraindications to extensive resection. In this study, we aim to identify predictive factors that correlate with nodal metastasis in patients affected by G1-G2 r-NETs. A retrospective analysis of G1-G2 r-NETs patients from eight tertiary Italian centers was performed. From January 1990 to January 2020, 210 patients were considered and 199 were included in the analysis. The data for nodal status were available for 159 cases. The nodal involvement rate was 9%. A receiver operating characteristic (ROC) curve analysis was performed to identify the diameter (>11.5 mm) and Ki-67 (3.5%), respectively, as cutoff values to predict nodal involvement. In a multivariate analysis, diameter > 11.5 mm and vascular infiltration were independently correlated with nodal involvement. A risk scoring system was constructed using these two predictive factors. Tumor size and vascular invasion are predictors of nodal involvement. In addition, tumor size > 11.5 mm is used as a driving parameter of better-tailored treatment during pre-operative assessment. Data from prospective studies are needed to validate these results and to guide decision-making in r-NETs patients in clinical practice.

JNETS clinical practice guidelines for gastroenteropancreatic neuroendocrine neoplasms: diagnosis, treatment, and follow-up: a synopsis

Neuroendocrine neoplasms (NENs) are rare neoplasms that occur in various organs and present with diverse clinical manifestations. Pathological classification is important in the diagnosis of NENs. Treatment strategies must be selected according to the status of differentiation and malignancy by accurately determining whether the neoplasm is functioning or nonfunctioning, degree of disease progression, and presence of metastasis. The newly revised Clinical Practice Guidelines for Gastroenteropancreatic Neuroendocrine Neoplasms (GEP-NENs) comprises 5 chapters-diagnosis, pathology, surgical treatment, medical and multidisciplinary treatment, and multiple endocrine neoplasia type 1 (MEN1)/von Hippel-Lindau (VHL) disease-and includes 51 clinical questions and 19 columns. These guidelines aim to provide direction and practical clinical content for the management of GEP-NEN preferentially based on clinically useful reports. These revised guidelines also refer to the new concept of "neuroendocrine tumor" (NET) grade 3, which is based on the 2017 and 2019 WHO criteria; this includes health insurance coverage of somatostatin receptor scintigraphy for NEN, everolimus for lung and gastrointestinal NET, and lanreotide for GEP-NET. The guidelines also newly refer to the diagnosis, treatment, and surveillance of NEN associated with VHL disease and MEN1. The accuracy of these guidelines has been improved by examining and adopting new evidence obtained after the first edition was published.

Development of a novel scoring system based on endoscopic appearance for management of rectal neuroendocrine tumors

BACKGROUND

The clinical significance of the endoscopic appearance of rectal neuroendocrine tumors (NETs) is poorly understood. We aimed to develop a novel scoring system based on endoscopic appearances to predict endoscopically advanced disease in patients with rectal NETs when initially diagnosed.

METHODS

Patients diagnosed with well-differentiated rectal NETs between January 2005 and December 2019 were retrospectively included. Logistic regression analyses were applied to study the relationship between endoscopic appearance and advanced disease. The whole dataset was randomly divided into training and validation sets, which were used to develop and validate a novel scoring system, respectively.

RESULTS

309 patients were included. The endoscopic appearance of rectal NETs was significantly associated with advanced disease (P < 0.001). A novel scoring system was developed based on endoscopic appearance, including tumor size, tumor shape, and mucosal surface, using the training set. The area under curve (AUC) of the scoring system to predict advanced disease was 0.953 (95 % confidence interval [CI] 0.915 - 0.991; P < 0.001) and 0.960 (95 %CI 0.905 - 1.000; P < 0.001) in the training and validation sets, respectively. Furthermore, the scoring system was significantly associated with tumor grade. Patients with high scores had significantly worse disease-free and overall survival than patients with low scores (P < 0.001).

CONCLUSION

This novel scoring system based on the endoscopic appearance of the primary tumor can help to accurately identify patients with endoscopically advanced disease who are not suitable for endoscopic resection. In addition, it is of great value in monitoring tumor recurrence and overall survival in patients with rectal NETs.

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.

Tumor Macroscopic Morphology Is an Important Prognostic Factor in Predicting Chemotherapeutic Efficacy and Clinical Outcomes of Patients With Colorectal Neuroendocrine Neoplasms, One Multicenter Retrospective Cohort Study

BACKGROUND AND AIMS

Locally advanced and metastatic colorectal neuroendocrine neoplasm (NEN) is a rare disease with a dismal prognosis. We aimed to explore the value of the macroscopic morphology of NENs in the management of TNM stage II-IV colorectal NENs, which has not been fully elucidated in previous reports.

METHODS

We retrospectively enrolled 125 eligible patients with TNM stage II-IV colorectal NENs who were diagnosed between 2000 and 2020 from three Chinese hospitals. All were categorized into either protruding or ulcerative NEN groups through endoscopic evaluation of their macroscopic morphology. Clinicopathological data were collected and compared between the two groups. Survival analysis was performed to assess the survival outcomes between the two groups.

RESULTS

A total of 77 and 48 patients had protruding and ulcerative NENs, respectively. Patients with ulcerative NENs had a larger median tumor size (P<0.001) and higher median Ki-67 index (P<0.001), and a larger proportion of these patients had grade G3 disease (P=0.001) and poorly differentiated neoplasms (P=0.001), as well as higher frequencies of T3 and T4 tumors (P=0.006) than patients with protruding NENs. In addition, patients with ulcerative NENs showed a much lower response to first-line chemotherapy [50% (95% CI: 27.3% - 72.7%) versus 20% (95% CI: 3.1% - 36.9%), P=0.03] and a worse 3-year progression-free survival (PFS) rate [19.7% (95% CI: 7.2% - 32.2%) versus 49.5% (95% CI: 37.5% - 61.5%), P=0.001] and 3-year overall survival (OS) rate [30.7% (95% CI: 15.6% - 45.8%) versus 76.9% (95% CI: 66.5% - 87.3%), P<0.001] than those with protruding NENs. The multivariate analysis results indicated that the macroscopic shape of NENs was an independent prognostic factor affecting both PFS (HR = 1.760, 95% CI: 1.024 - 3.026, P = 0.04) and OS (HR = 2.280, 95% CI: 1.123 - 4.628, P = 0.02).

CONCLUSIONS

Ulcerative NENs were more malignant and chemotherapy resistant than protruding NENs. Tumor macroscopic morphology is a valuable prognostic factor for stage II-IV colorectal NENs.

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

BACKGROUND/AIM

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

The outcomes of modified endoscopic mucosal resection and endoscopic submucosal dissection for the treatment of rectal neuroendocrine tumors and the value of endoscopic morphology classification in endoscopic resection

BACKGROUND

To compare the outcomes of modified endoscopic mucosal resection (m-EMR) and endoscopic submucosal dissection (ESD) for rectal neuroendocrine tumors (NETs) and evaluate the value of endoscopic morphology classification in endoscopic resection (ER).

METHODS

Patients with rectal NET diameters less than 2 cm who were treated between April 2007 and January 2019 were enrolled. The endoscopic morphology of rectal NETs was classified based on the endoscopic views. Patients who underwent ESD and m-EMR were compared. Baseline characteristics as well as en bloc resection, complete resection, the procedure time, adverse events and the risk factors associated with incomplete resection were analyzed.

RESULTS

A total of 429 patients with 449 rectal NETs were enrolled for the classification of endoscopic morphology and were classified into four types (Ia, IIb, II, and III). There were 79 patients in the m-EMR group and 259 patients in the ESD group before matching. Propensity score matching created 77 pairs between the two groups that were well balanced. The mean procedure time was significantly shorter for m-EMR than for ESD (9.1 ± 4.4 min vs 16.0 ± 7.9 min, P = 0.000). The rates of en bloc resection (98.7% vs 100%; P = 1.000), complete resection (90.9% vs 93.5%, P = 0.548) and adverse events (2.6% vs 2.6%, P = 1.000) were similar between the two groups. Univariate and multivariate analyses showed that histopathological grade and endoscopic morphology were associated with incomplete resection.

CONCLUSION

Both ESD and m-EMR are effective and safe for the treatment of rectal NETs. Endoscopic morphology should be considered along with histopathological grade for ER.

A small, well-differentiated rectal neuroendocrine tumor with multiple lymph node metastases: A case report

The incidence of rectal neuroendocrine tumor (NET), which is often diagnosed during routine surveillance endoscopy, is increasing. The majority of these tumors are small and asymptomatic, possessing benign features with favorable prognoses. At present, small rectal NETs without high-risk factors are typically treated by local resection, including endoscopic mucosal resection, endoscopic submucosal dissection, or transanal endoscopic microsurgery, with or without additional imaging follow-up by abdominal computed tomography or magnetic resonance imaging. The present study, however, describes a case of a small rectal NET without any known risk factors, which was accompanied by substantial locoregional lymph node metastasis, underscoring the importance of imaging studies for rectal NETs.

Diagnosis and Management of Rectal Neuroendocrine Tumors

The incidence of rectal neuroendocrine tumors (NETs) has increased by almost ten-fold over the past 30 years. There has been a heightened awareness of the malignant potential of rectal NETs. Fortunately, many rectal NETs are discovered at earlier stages due to colon cancer screening programs. Endoscopic ultrasound is useful in assessing both residual tumor burden after retrospective diagnosis and tumor characteristics to help guide subsequent management. Current guidelines suggest endoscopic resection of rectal NETs ≤10 mm as a safe therapeutic option given their low risk of metastasis. Although a number of endoscopic interventions exist, the best technique for resection has not been identified. Endoscopic submucosal dissection (ESD) has high complete and en-bloc resection rates, but also an increased risk of complications including perforation. In addition, ESD is only performed at tertiary centers by experienced advanced endoscopists. Endoscopic mucosal resection has been shown to have variable complete resection rates, but modifications to the technique such as the addition of band ligation have improved outcomes. Prospective studies are needed to further compare the available endoscopic interventions, and to elucidate the most appropriate course of management of rectal NETs.

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.

The anthropometric definition of the rectum is highly variable

PURPOSE

The precise definition of the rectum is essential for localizing colorectal pathology, yet current definitions are nebulous. The objective of this study is to determine the anthropometric definition of common pelvic landmarks in relation to patient characteristics.

METHODS

Seventy-one patients underwent open proctectomy with intra-operative measurements from the anal verge to various pelvic landmarks, and patient characteristics were evaluated. Analyses were performed using Spearman correlation and Wilcoxon rank sum.

RESULTS

The mean landmark distance was dentate line = 1.7 cm (range 0.8-4.0 cm), puborectalis muscle = 4.2 cm (range 2.0-8.0 cm), anterior peritoneal reflection = 13.2 cm (range 8.5-21.0 cm), sacral promontory = 17.9 cm (range 13.0-26.0 cm), and confluence of the taenia = 25.5 cm (range 16.0-44.0 cm). Men had longer mean distances to the dentate line (p = 0.0003), puborectalis muscle (p = 0.03), and anterior peritoneal reflection (p = 0.02). Patient weight significantly correlated with distance to all landmarks except for the confluence of the taenia, which did not correlate with any patient factor.

CONCLUSIONS

The location of common pelvic landmarks is highly variable. The use of predefined absolute measurements from the anal verge to localize rectal pathology is inaccurate and fails to account for patient variability.

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.

Neuroendocrine Rectal Tumors: Main Features and Management

The incidence of neuroendocrine tumors of the rectum has been increasing in the last decades, partly due to improved investigation. They are mostly well-differentiated small tumors with a rather good overall prognosis. In the last few years, some aspects of neuroendocrine tumors have been evolving. In 2010, the World Health Organization proposed a new classification, indicating that these tumors, as a category, should be considered malignant. Afterwards the European Neuroendocrine Tumor Society published their guidelines for the management of colorectal neoplasms. Treatment algorithm is mainly based on tumor size and grading and, in general, well-differentiated rectal tumors <2 cm can be endoscopically resected. Endorectal ultrasound plays a particularly important role by accurately assessing tumor size and depth of invasion prior to resection. There are no specific recommendations on the optimal endoscopic resection method, but data from recent studies suggests that modified endoscopic mucosal resection techniques and endoscopic submucosal dissection have superior complete resection rates.

Clinicopathological analysis of colorectal carcinoid tumors and patient outcomes

Background

Colorectal carcinoid tumors are often described as being low-grade malignant. The objective of the current study was to address the clinicopathological features and outcomes of patients with colorectal carcinoid tumors.

Methods

A total of 63 patients with colorectal carcinoid tumors were identified and evaluated using surgical pathology files and medical records between January 2000 and June 2012 at the Veterans General Hospital, Taipei, Taiwan.

Results

The median age of the 63 patients was 57.0 years; 38 (60.3%) were male and 25 (39.7%) female. The rectum was the most common tumor site (90.5%). Tumor size was 10.8 ± 7.4 mm, ranging from 2 to 50 mm in diameter. There were 40 patients (63.5%) who received endoscopic treatment for a tumor size of 7.7 ± 4.0 mm, 15 (23.8%) who underwent transanal excision for a mean size of 9.2 ± 4.5 mm and eight (12.7%) who underwent radical surgical resection (mean size: 29.5 ± 13.0 mm). Lymph node metastasis was significantly associated with tumor size. Totally distant metastases (liver) were demonstrated in four (6.3%), patients with mean tumor size of 31.3 ± 9.4 mm (20 to 50 mm). The extent of the disease was associated with survival and the five-year overall survival rate was 92.1%.

Conclusions

With widespread colorectal cancer screening, heightened awareness and improved diagnostic modalities, the incidence of colorectal carcinoid tumors will continue to increase. We demonstrated that small-sized colorectal carcinoid tumors and those localized in the mucosa or submucosa may be safely and effectively removed via endoscopic or transanal local excision.

Rectal carcinoids: a systematic review

BACKGROUND

Rectal carcinoids are increasing in incidence worldwide. Frequently thought of as a relatively benign condition, there are limited data regarding optimal treatment strategies for both localized and more advanced disease. The aim of this study was to summarize published experiences with rectal carcinoids and to present the most current data.

METHODS

Following PRISMA guidelines, an electronic literature search performed of PubMed, Medline, Embase, and the Cochrane Library using the terms "rectum" or "rectal" AND "carcinoid" over a 20-year study period from January 1993 to May 2013. Non-English-language studies, animal studies, and studies of fewer than 100 patients were excluded. Study end points included demographic information, tumor features, intervention and outcomes. All included articles were quality assessed.

RESULTS

Using the search parameters and exclusions as outlined above, a total of 14 articles were identified for detailed analysis. The quality of articles was low/moderate for all included scoring 9 to 17 of 27. The articles included 4,575 patients diagnosed with a rectal carcinoid. Approximately 80% of tumors were <10 mm, 15% 11-20 mm, and 5% >20 mm. Eight percent of patients presented with regional lymph node metastases, and 4% presented with distant metastases. Tumor size >10 mm, and muscular and lymphovascular invasion are independently associated with an increased risk of metastases. The 5-year survival was 93% in patients presenting with localized disease and 86% overall.

CONCLUSIONS

Small tumors up to 10 mm without any adverse features can be treated with endoscopic or local excision. The treatment of carcinoids between 10 and 20 mm is still contentious, but those up to 16 mm without adverse feature are suitable for local/endoscopic excision followed by careful histopathological assessment. Those >20 mm or with adverse features require radical surgery with mesorectal clearance in suitable patients.

Endoscopic resection therapies for rectal neuroendocrine tumors: a systematic review and meta-analysis

BACKGROUND AND AIM

Among various endoscopic resection therapies, including conventional endoscopic mucosal resection (EMR) only with a snare after submucosal injection, modified EMR (m-EMR) with other assistant devices such as a ligation band or a suction cap, and endoscopic submucosal dissection (ESD), we aimed to study which is the best choice for rectal neuroendocrine tumors.

METHODS

A broad literature research was performed, and a systematic review and meta-analysis were conducted.

RESULTS

Ten retrospective studies with 650 patients were included. Complete resection rates were significantly higher in the ESD group compared with the EMR group (relative risk [RR] 0.89, 95% confidence interval [CI] [0.79, 0.99]), in the m-EMR group compared with the conventional EMR group (RR 0.72, 95% CI [0.60, 0.86]), and was comparable between the ESD group and the m-EMR group (RR 1.03, 95% CI [0.95, 1.11]). Procedure time was significantly longer in the ESD group than in the EMR group (standard mean differences -1.37, 95% CI [-1.99, -0.75]), but there was no significant difference between that of the m-EMR group and ESD group (standard mean differences -1.50, 95% CI [-3.14, 0.14]). Local recurrence occurred in five cases in the EMR group (5/328) and did not occur in the ESD group (0/209).

CONCLUSIONS

ESD or m-EMR techniques could be applied to rectal neuroendocrine tumors with indications for endoscopic treatment. m-EMR procedures appear to be comparable with ESD in the treatment of rectal neuroendocrine tumors. However, the findings have to be carefully interpreted due to the lower level of evidence.

Factors associated with lymph node metastasis in radically resected rectal carcinoids: a systematic review and meta-analysis

BACKGROUND

Although various guidelines regarding neuroendocrine tumors were released, treatment for rectal neuroendocrine tumors with size between 1 and 2 cm has not been explicitly elucidated. The determinant factor of the choice between endoscopic resection and radical surgery is whether lymph node involvement exists.

AIM

This study aims to explore factors associated with lymph node involvement in rectal neuroendocrine tumors by conducting a meta-analysis.

METHODS

A broad literature research of Pubmed, Embase&Medline, and The Cochrane Library was performed, and systematic review and meta-analysis about factors associated with lymph node involvement were conducted.

RESULTS

Seven studies were included in this meta-analysis. Tumor size > 1 cm (odds ratio (OR) 6.72, 95% confidence interval (CI) [3.23, 14.02]), depth of invasion (OR 5.06, 95% CI [2.30, 11.10]), venous invasion (OR 5.92, 95% CI [2.21, 15.87]), and central depression (OR 3.00, 95% CI [1.07, 8.43]) were significantly associated with lymph node involvement.

CONCLUSION

The available clinical evidence suggests that tumor size > 1 cm, invasion of muscularis properia, venous invasion, and central depression could be risk factors of lymph node involvement, while other factors reported by few studies need further research.

Treatment strategy for rectal carcinoids: a clinicopathological analysis of 229 cases at a single cancer institution

BACKGROUND AND AIM

A treatment strategy for tumors with only venous invasion and characteristics of small rectal carcinoids with metastasis have not been clearly documented. The present study aims to determine the risk factors for lymph node metastasis and to elucidate characteristics of small tumors with metastasis.

METHODS

We investigated a total of 229 patients with rectal carcinoids. The relationship between each clinicopathological variable and the presence of lymph node metastasis was evaluated.

RESULTS

Tumor size (larger than 10 mm), presence of central depression, depth of tumor invasion, lymphatic invasion, and venous invasion were significantly associated with the incidence of lymph node metastasis (P < 0.001). Multivariate analysis revealed that tumor size (odds ratio: 63.3, P < 0.001) and venous invasion (odds ratio: 40.9, P < 0.001) were independently predictive of lymph node metastasis. In 204 patients with small (no larger than 10 mm) tumors, 10 patients had lymph node metastasis. All 10 tumors had low proliferation values indicated by mitosis and Ki-67 index. Multivariate analysis for the 204 patients revealed that only venous invasion was independently associated with metastasis (odds ratio: 40.1, P < 0.001). Five-year disease free survival rates of the total patients with metastasis and without metastasis were 81.1% and 95.5%, respectively (P < 0.001, log-rank test).

CONCLUSIONS

Venous invasion as well as tumor size and lymphatic invasion indicates high malignant potential to metastasize to lymph node and would provide useful information in considering the addition of radical surgery. Postoperative pathological examinations of specimens obtained by local resection are very important to avoid underestimation.

Clinical characteristics of colorectal carcinoid tumors

PURPOSE

The carcinoid tumor was recently categorized as a malignant disease due to its possibility of metastasis. This study was aimed to investigate the clinical characteristics and the metastatic rate of colorectal carcinoid tumors.

METHODS

Charts were reviewed for 502 patients diagnosed with and treated for colorectal carcinoid tumors between January 2006 and December 2009. The location, size, depth and metastatic status of the tumors were collected.

RESULTS

Including 24 synchronous tumors from 12 patients, 514 carcinoid tumors were removed. Most of them were found in the rectum (97.3%). The male-to-female ratio was 1.38 to 1, and mean age was 50.2 ± 11.4 years. The mean tumor size was 5.8 ± 3.6 mm. Less than 10-mm-sized tumors had a 1.95% lymph node metastatic rate; tumors with sizes from 10 mm to 20 mm and larger than 20 mm had 23.5% and 50% lymph node metastatic rates, respectively. Two cases had distant metastasis; one with a 22-mm-sized tumor metastasized to the liver, and the other with a 20-mm-sized tumor metastasized to the peritoneum. Among 414 patients who completed metastatic studies, 93.8% were classified as stage I, 0.9% as stage II, 4.8% as stage III and 0.5% as stage IV.

CONCLUSION

Colorectal carcinoid tumors smaller than 10 mm have a low rate of lymph node metastasis, but those sized 10 mm or larger incur significant risk. Further investigation regarding additional risk factors should be done to develop proper treatment guidelines for these tumors.

Clinicopathological characteristics of rectal carcinoids

PURPOSES

Carcinoids are heterogeneous neuroendocrine tumors with malignant potential. The rectum is the third most common location for gastrointestinal carcinoids. We assessed the clinicopathological characteristics of rectal carcinoids.

METHODS

A retrospective study of 203 patients treated for rectal carcinoids at the Asan Medical Center, Seoul, Republic of Korea from 1991 to 2007.

RESULTS

The patients were on average 51 (18-83) years old. The male-to-female ratio was 1.48:1. Over half (62.1%) of the patients were asymptomatic. The most frequent symptoms in the symptomatic patients were abdominal pain (11.1%) and hematochezia (10.7%). Local excision was applied to 92.1%, low anterior resection to 4.9%, and biopsy only to 3.0% of total patients. Initially, 4.4% presented with distant metastasis. Distant metastasis rates for tumors < or =1 cm, >1 to < or =2 cm, and >2 cm were 1.7% (3/177), 15.0% (3/20), and 50.0% (3/6), respectively. In the follow-up period, three patients showed recurrences. The size, lymphovascular invasion, perineural invasion, and T and N stages were associated with distant metastasis. The overall 5-year survival rate was 94.0%. The TNM stage and presence of lymphovascular invasion were associated with lower survival.

CONCLUSIONS

The chance that a rectal carcinoid will develop distant metastases increases as the tumor increases in size, lymphovascular invasion or perineural invasion is present, and T and N stages increase. The TNM stage and presence of lymphovascular invasion were associated with lower survival. Treatment plan should be chosen carefully considering above factors.