Rectal neuroendocrine tumors: Current advances in management, treatment, and surveillance

Endoscopic therapy versus surgical resection for elderly patients with colorectal neuroendocrine tumors

BACKGROUND

Endoscopic therapy (ET) and surgical resection (SR) are common surgical methods for the treatment of colorectal neuroendocrine tumors (CRNETs). However, for elderly patients, it remains unclear which surgical method yields better long-term outcomes.

METHODS

Elderly patients ≥ 65 years with CRNETs diagnosed from 2000 to 2020 were identified from the Surveillance, Epidemiology, and End Results database. Propensity score matching (PSM) was used to minimize selection bias. The Kaplan-Meier method and Cox proportional hazards models were utilized to evaluate the effects of diverse demographic and clinical factors on overall survival (OS) and cancer-specific survival (CSS).

RESULTS

A total of 2214 patients were included in the study, with 1417 patients in the ET group and 797 patients in the SR group. After PSM, the ET group outperformed the SR group in terms of OS (hazard ratio [HR] 0.56, 95% confidence interval [CI] 0.44-0.70) and CSS (HR 0.21, 95% CI 0.11-0.40). Similarly, the ET group maintained its advantage in mean 1-, 3-, and 5-year OS and CSS rates compared to the SR group (P < 0.001). Multivariate Cox regression analysis identified age, sex, grade, marital status, and treatment modality as independent risk factors affecting OS, while age, sex, marital status, and treatment modality were identified as independent risk factors affecting CSS.

CONCLUSIONS

ET offered superior long-term outcomes for elderly patients ≥ 65 years with CRNETs.

Deep learning model with pathological knowledge for detection of colorectal neuroendocrine tumor

Colorectal neuroendocrine tumors (NETs) differ significantly from colorectal carcinoma (CRC) in terms of treatment strategy and prognosis, necessitating a cost-effective approach for accurate discrimination. Here, we propose an approach for distinguishing between colorectal NET and CRC based on pathological images by utilizing pathological prior information to facilitate the generation of robust slide-level features. By calculating the similarity between morphological descriptions and patches, our approach selects only 2% of the diagnostically relevant patches for both training and inference, achieving an area under the receiver operating characteristic curve (AUROC) of 0.9974 on the internal dataset, and AUROCs of 0.9724 and 0.9513 on two external datasets. Our model effectively identifies NETs from CRCs, reducing unnecessary immunohistochemical tests and enhancing the precise treatment for patients with colorectal tumors. Our approach also enables researchers to investigate methods with high accuracy and low computational complexity, thereby advancing the application of artificial intelligence in clinical settings.

Endoscopic submucosal dissection for rectal neuroendocrine tumours: A multicentric retrospective study

INTRODUCTION

Endoscopic Submucosal Dissection (ESD) has been reported as a feasible and effective treatment for Rectal Neuroendocrine Tumours (R-NETs). However, most of the experience on the topic comes from retrospective tertiary centre from Eastern Asia. Data on ESD for R-NETs in Western centres are lacking.

MATERIALS AND METHODS

This is a retrospective study, including patients who underwent endoscopic resection of R-NETS by ESD between 2015 and 2020 in Western Centres. Important clinical variables such as demographic, size of R-NETs, histological type, presence of lymphovascular invasion or distant metastasis, completeness of the endoscopic resection, recurrence, and procedure related complications were recorded.

RESULTS

40 ESD procedure on R-NETs from 39 patients from 8 centres were included. Mean R-NETs size was 10.3 mm (SD 4.01). Endoscopic en-bloc resection was achieved in 39/40 ESD (97.5 %), R0 margin resection was obtained in 87.5 % (35/40) of the procedures, one patient was referred to surgery for lymphovascular invasion, two procedures (5 %) reported significant episodes of bleeding, whereas a perforation occurred in one case (1/40, 2.5 %) managed endoscopically. Recurrence occurred in 1 patient (2.5 %).

CONCLUSION

ESD is an effective and safe treatment for R-NETs in western centres.

Risk factors for regional lymph node metastasis in rectal neuroendocrine tumors: a population-based study

Introduction

The identification of risk factors for regional lymph node (r-LN) metastasis in rectal neuroendocrine tumors (R-NETs) remains challenging. Our objective was to investigate the risk factors associated with patients diagnosed with R-NETs exhibiting r-LN metastasis.

Methods

Patient information was obtained from the Surveillance, Epidemiology, and End Results (SEER) database, complemented by data from the West China Hospital (WCH) databases. The construction cohort comprised patients diagnosed with R-NETs from the SEER database, while cases from the WCH database were utilized as the validation cohort. A novel nomogram was developed to predict the probability of r-LN metastasis, employing a logistic regression model.

Results

Univariate analysis identified four independent risk factors associated with poor r-LN metastasis: age (HR = 1.027, p < 0.05), grade (HR = 0.010, p < 0.05), T stage (HR = 0.010, p < 0.05), and tumor size (HR = 0.005, p < 0.05). These factors were selected as predictors for nomogram construction.

Discussion

The novel nomogram serves as a reliable tool for predicting the risk of r-LN metastasis, providing clinicians with valuable assistance in identifying high-risk patients and tailoring individualized treatments.

Clinicopathological and molecular differences between stage IV screen-detected and interval colorectal cancers in the Flemish screening program

Introduction

Interval cancer (IC) is an important quality indicator in colorectal cancer (CRC) screening. Previously, we found that fecal immunochemical test (FIT) ICs are more common in women, older age, right-sided tumors, and advanced stage. Here, we extended our existing stage IV patient cohort with clinicopathological and molecular characteristics, to identify factors associated with FIT-IC.

Methods

Logistic regression models were fit to identify variables associated with the odds of having a stage IV FIT-IC. Multivariate models were corrected for gender, age, and location.

Results

A total of 292 screen-detected (SD) CRCs and 215 FIT-IC CRCs were included. FIT-IC CRC had 5 fold higher odds to be a neuroendocrine (NET) tumor and 2.5 fold higher odds to have lymphovascular invasion. Interestingly, some variables lost significance upon accounting for location. Thus, tumor location is a critical covariate that should always be included when evaluating factors related to FIT-IC.

Conclusions

We identified NETs and lymphovascular invasion as factors associated with increased odds of having a stage IV FIT-IC. Moreover, we highlight the importance of tumor location as a covariate in evaluating FIT-IC related factors. More research across all stages is needed to clarify how these insights might help to optimize the Flemish CRC screening program.

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.

Clinical outcomes after endoscopic resection and the risk of lymph node metastasis in rectal neuroendocrine tumors: a single-center retrospective study

BACKGROUND AND AIM

The incidence of rectal neuroendocrine tumors (R-NETs) has increased in recent years. However, the predictors of lymph node (LN) metastasis and clinical outcomes, particularly following endoscopic treatment, remain unclear. Our study aims to elucidate the potential risk factors for LN metastasis and the clinical outcomes of patients undergoing endoscopic resection in R-NETs.

METHODS

A total of 128 patients with R-NETs were retrospectively identified from a single center between June 2012 and December 2021. Risk factors for LN metastasis in R-NETs were analyzed using multivariate analysis. Additionally, the clinical outcomes of endoscopic resections in patients with R-NETs were assessed.

RESULTS

In our study, 128 patients with R-NETs were retrospectively analyzed. The risk factors for LN metastasis determined by multivariate analysis were tumor size and patient age at diagnosis. Among the 111 patients treated with endoscopic resection and with tumor margin records available, 92 underwent endoscopic submucosal dissection (ESD) and 19 underwent conventional endoscopic mucosal resection (EMR). There was no significant difference between the two groups regarding the positive rates of basal tumor margin and lateral tumor margin. Furthermore, 64 patients who underwent endoscopic resection for R-NETs were successfully followed up (range, 1.64-76.71 months), during which only one patient developed local recurrence.

CONCLUSION

Tumor size and age at diagnosis were predictors for LN metastasis of R-NETs. Both ESD and EMR are alternative techniques with a favorable prognosis for R-NETs, even in cases with positive resection margins. However, due to the relatively small number of patients undergoing EMR and missing data in follow-up protocols, definitive conclusions require further large-scale studies.

Pathological Characteristics, Management, and Prognosis of Rectal Neuroendocrine Tumors: A Retrospective Study from a Tertiary Hospital

BACKGROUND

Rectal neuroendocrine tumors (rNENs) are rare, constituting 1-2% of rectal tumors, and are often asymptomatic, leading to challenges in early diagnosis. Current management guidelines recommend endoscopic resection for small lesions and surgical intervention for larger or high-risk tumors. This study aims to retrospectively analyze the pathological characteristics, management, and prognosis of rNEN patients.

METHODS

Data from the Neuroendocrine Tumor Registry at a tertiary hospital in Milan, Italy from 2005 to 2023 were retrospectively analyzed. Patient demographics, disease characteristics, pathology findings, treatment details, and surveillance data were collected. Statistical analyses included descriptive statistics, multivariable binary logistic regression, and Kaplan-Meier survival analysis.

RESULTS

Forty-five patients were included, 53.3% male with a mean age of 57.5 years. Most patients were asymptomatic, with incidental diagnosis during colonoscopy. Endoscopic excision was the primary treatment modality (77.8%), with surgical resection reserved for incomplete or inappropriate endoscopic resections. Disease progression occurred in 13 patients (28.9%), with tumor-related mortality of 22.2%. Kaplan-Meier analysis showed 5- and 10-year survival rates of 68.8% and 59.1%, respectively, with corresponding progression-free survival rates of 72.8% and 54.0%. Tumor stage was significantly associated with disease progression on multivariable analysis (OR = 7.230, p = 0.039).

CONCLUSIONS

This study highlights the heterogeneous presentation and prognosis of rNENs, with a substantial proportion diagnosed incidentally. Endoscopic management was predominantly utilized, aligning with current guidelines for localized tumors. Tumor stage emerged as a significant predictor of disease progression, emphasizing the importance of accurate staging for optimal management. Further research is warranted to refine management protocols and validate these findings.

Risk factors for and prognostic impact of lateral pelvic lymph node metastasis in patients with rectal neuroendocrine tumors: a single-center retrospective analysis of 214 cases with radical resection

PURPOSE

Lateral pelvic lymph node (LPLN) metastasis of rectal neuroendocrine tumors (NETs) is rare, with unknown oncological features. We investigated the oncological impact of LPLN metastasis in patients with rectal NETs.

METHODS

This study included 214 patients with rectal NETs who underwent curative surgery. We evaluated their clinicopathological characteristics and short- and long-term outcomes.

RESULTS

LPLN dissection was performed in 15 patients with LPLN swelling ≥ 7 mm (preoperative imaging); 12 patients had LPLN metastases, 6 of whom had LPLN metastases without mesorectal lymph node metastases (skip metastasis). The short-term outcomes were similar between the groups with and without LPLN dissection. The median follow-up period was 59.4 months, and patients with LPLN metastasis showed significantly shorter disease-free and overall survival rates than those without metastasis. Among 199 patients who did not undergo LPLN dissection, only 1 had LPLN recurrence. In a univariate analysis, tumor depth, tumor grade, and LPLN metastasis were associated with the overall survival. In the multivariate analysis, only LPLN metastasis was an independent predictor of the overall survival.

CONCLUSIONS

LPLN metastasis is a poor prognostic factor for patients with rectal NETs. LPLN enlargement can be considered an indication for dissection, owing to its high rate of metastasis and associated poor prognosis.

Laparoscopic versus open surgery for rectal neuroendocrine tumors: a multicenter real-world study

BACKGROUND

Owing to the lack of evidence-based medical studies with large sample sizes, the surgical approach for the radical resection of rectal neuroendocrine tumors remains controversial.

METHODS

We retrospectively collected the medical records of patients with rectal neuroendocrine tumors who underwent radical resection at 17 large tertiary care hospitals in China between January 1, 2010, and April 30, 2022. All patients were divided into laparoscopic and open surgery groups. After propensity score matching to reduce confounders, the postoperative and oncologic outcomes were compared between the groups.

RESULTS

We enrolled 174 patients with rectal neuroendocrine tumors who underwent radical surgery. After random matching, 124 patients were included in the comparison (62, laparoscopic surgery group; 62, open surgery group). The laparoscopic surgery group had fewer complications (14.5% vs. 35.5%, P = 0.007) and superior relapse-free survival (P = 0.048). Subgroup analysis revealed that the laparoscopic surgery group had fewer complications (10.9% vs. 34.7%, P = 0.004), shorter postoperative hospital stays (9.56 ± 5.21 days vs. 12.31 ± 8.61 days, P = 0.049) and superior relapse-free survival (P = 0.025) in the rectal neuroendocrine tumors ≤ 4 cm subgroup.

CONCLUSIONS

Laparoscopic surgery was associated with improved postoperative outcomes and oncologic prognosis for patients with rectal neuroendocrine tumors ≤ 4 cm; it can serve as a safe and feasible option for radical surgery of rectal neuroendocrine tumors.

Outcome of Endoscopic Resection of Rectal Neuroendocrine Tumors ≤ 10 mm

BACKGROUND AND AIM

Guidelines suggest endoscopic resection for rectal neuroendocrine tumors (rNETs) < 10 mm, but the most appropriate resection technique is unclear. In real-life clinical practice, the endoscopic removal of unrecognized rNETs can take place with "simple" techniques and without preliminary staging. The aim of the current study is to report our own experience at a referral center for both neuroendocrine neoplasms and endoscopy.

METHODS

Retrospective analyses of polypectomies were performed at the Humanitas Research Hospital for rNETs (already diagnosed or previously unrecognized).

RESULTS

A total of 19 patients were included, with a median lesion size of 5 mm (range 3-10 mm). Only five lesions were suspected as NETs before removal and underwent endoscopic ultrasound (EUS) before resection, being removed with advanced endoscopic techniques. Unsuspected rNETs were removed by cold polypectomy in eleven cases, EMR in two, and biopsy forceps in one. When described, the margins were negative in four cases, positive in four (R1), and indeterminate in one. The median follow-up was 40 months. A 10 mm polypoid lesion removed with cold snare polypectomy (G2 R1) needed subsequent surgery. Eighteen patients underwent EUS after a median time of 6.5 months from resection. The EUS identified local recurrence after 14 months in a 7 mm polypoid lesion removed with cold snare polypectomy (G1 R1); the lesion was treated with cap-assisted EMR. For all the other lesions, the follow-up was negative.

CONCLUSIONS

When rNETs are improperly removed without prior staging, caution must be exercised. The data from our cohort suggest that even if inappropriate resection had happened, patients may be safely managed with early EUS evaluation.

Management & surveillance of rectal neuroendocrine tumours: a single-centre retrospective analysis

BACKGROUND

Rectal neuroendocrine tumours (rNETs) are rare but are increasing in incidence. Current management and surveillance recommendations are based on low-grade evidence. Follow-up practices are often inconsistent and costly. This retrospective study analyses a single-centre's experience with rNETs to assess incidence, management practices, outcomes, and guideline adherence.

METHODS

This is a single-centre retrospective study from Queensland Australia, spanning from 2012 to 2023. Twenty-eight rNET cases met inclusion criteria. Examined parameters included incidence, management, outcomes and adherence to European Neuroendocrine Tumour Society (ENETS) guidelines. R1 resection rate was analysed for associations with resection technique and lesion recognition and recurrence rate was assessed in all patients.

RESULTS

This study shows an increasing incidence of rNETs during the study period, reflecting a global trend. R1 resection rate at initial endoscopy was 75%. There was a general lack of advanced endoscopic techniques utilized and poor lesion recognition, however a statistically significant correlation was not established between these factors and an R1 result (P < 0.05). Most patients with an R1 result had subsequent re-resection to render the result R0, however five patients (33%) underwent surveillance with no reports of recurrence on follow-up. Overall, follow-up practices in our cohort were inconsistent and did not adhere to guidelines.

CONCLUSION

rNETs are increasing in incidence, emphasizing the need for standardized management and surveillance. Further training is required for rNET recognition and advanced endoscopic resection techniques. Further research is required to assess long-term outcomes in surveilled R1 cases, understand optimal endoscopic resection techniques and further develop local surveillance guidelines.

Optimization of Endoscopic Submucosal Dissection and Endoscopic Mucosal Resection Strategies for Rectal Neuroendocrine Tumors Within 20 mm

AIMS

No consensus regarding the optimal endoscopic resection approach for rectal neuroendocrine tumors (R-NETs) measuring 10-20 mm, this study aims to investigate this issue.

METHODS

Patients with R-NETs underwent either endoscopic mucosal resection (EMR) or endoscopic submucosal dissection (ESD). The primary endpoint was the complete resection rate, and the secondary endpoints were surgery-related complications and long-term outcomes.

RESULTS

96 patients met the inclusion criteria, 84 patients completed endoscopic resection, and 5 patients were excluded. 79 patients were enrolled and divided into EMR (n = 21) and ESD groups (n = 58). 100% of ESD excisions reached the primary endpoint, while 90.5% of EMR. Endoscopic submucosal dissection can achieve higher R0 rate and lower positive margin rate than EMR. The mean operative time of ESD and EMR was 35.22 ± 8.96 min and 13.14 ± 3.26 min, respectively. The complication rates of ESD and EMR were 3.4% and 4.8%, respectively. For R-NETs between 10 mm and 20 mm, the R0 rate of ESD was significantly higher than that of EMR (100% vs 71.4%, P = .01) and the margin positive rate of ESD was significant lower than that of EMR (4.8% vs 42.9%, P < .05). Both ESD and EMR obtained 100% R0 resection of less than 10 mm R-NET. The median follow-up was 13 months (3-84 months); 1 patient relapsed 25 months after EMR and was re-treated with ESD.

CONCLUSION

For R-NETs with a diameter less than 10 mm, both EMR and ESD were safe and effective and EMR is convenient and fast, with advantages. ESD offers superiority for R-NETs between 10 and 20 mm and can be considered as the preferred method.

Diagnostic performance and clinical impact of 18F-AlF-NOTA-octreotide in a large cohort of patients with neuroendocrine neoplasms: A prospective single-center study

Purpose: Somatostatin receptor imaging with 18F-AlF-NOTA-octreotide (18F-AlF-OC) has shown promising performance in neuroendocrine neoplasms (NENs). In this study, we aim to investigate the diagnostic performance and clinical impact of 18F-AlF-OC in a large prospective cohort of patients with NEN. Methods: Between January 2023 and November 2023, a total of 219 patients with confirmed or suspected NEN were enrolled prospectively and underwent 18F-AlF-OC PET/CT at 2 h post-injection. The primary endpoint was the diagnostic performance, including sensitivity, specificity, and accuracy. An additional primary endpoint was the impact of 18F-AlF-OC on clinical management. The reference standard was based on the results of histopathology or radiological follow-up. Results: 205 patients were included in the final analysis. The patient-level sensitivity, specificity, and accuracy of 18F-AlF-OC PET/CT compared with contrast-enhanced CT/MRI were 90.5% vs. 81.8%, 93.1% vs. 71.1%, and 91.2% vs. 79.4%, respectively. 26 patients had tiny gastrointestinal NENs (smaller than 1 cm in diameter). The patient-based sensitivity of 18F-AlF-OC PET/CT and contrast-enhanced CT/MRI were 61.5% (16/26) and 37.5% (9/24), respectively. The smallest diameter of gastrointestinal NEN detected by 18F-AlF-OC PET/CT was 0.6 cm in the rectum, 0.3 cm in the stomach, and 0.5 cm in the duodenum. 18F-AlF-OC PET/CT results led to changes in clinical management in 19.5% of patients (40/205), owing mainly to new or unexpected findings compared to contrast-enhanced CT/MRI. Conclusion: 18F-AlF-OC PET/CT demonstrated great diagnostic performance in patients with NEN, particularly for detecting tiny gastrointestinal NEN. Furthermore, 18F-AlF-OC PET/CT impacted the therapeutic management in 19.5% of patients. Our results further validate the role of 18F-AlF-OC as a somatostatin receptor imaging tracer in clinical practice.

Impact of grade on workup of rectal neuroendocrine tumors: a retrospective cohort study : Grade impact on workup of rectal NETs

BACKGROUND

Rectal neuroendocrine tumors (RNETs) are often discovered on screening colonoscopy. Indications for staging and definitive resection are inconsistent in current guidelines. We evaluated the role of grade in guiding staging and procedural decision-making.

METHODS

Patients with biopsy confirmed RNETs between 2004 and 2015 were reviewed. Baseline characteristics, staging investigations (biochemical and imaging), and endoscopic/surgical treatment were recorded. Associations between grade, preoperative staging, interventions, and survival were determined using Fisher-Freeman-Halton Exact, log-rank, and Kaplan-Meier analysis.

RESULTS

Amongst 139 patients with RNETs, 9% were aged ≥ 75 years and 44% female. Tumor grade was: 73% grade 1 (G1), 18%, grade 2 (G2) and 9% grade 3 (G3). Staging investigations were performed in 52% of patients. All serum chromogranin A and 97% of 24-hour urine 5-hydroxyindoleacetic acid tests were normal. The large majority of staging computed tomography (CT) scans were negative (76%) with subgroup analysis showing no G1 patients with CT identified distant disease compared with 38% of G2 and 50% of G3 patients (p < 0.001). G1 patients were more likely to achieve R0/R1 resections compared to G2 (95% vs. 50%, p < 0.001) and G1 patients had significantly better 5-year overall survival (G1: 98%, G2: 67%, G3: 10%, p < 0.001).

CONCLUSION

Tumor grade is important in preoperative workup and surgical decision-making. Biochemical staging may be omitted but staging CT should be considered for patients with grade ≥ 2 lesions. Anatomic resections should be considered for patients with grade 2 disease.

Endoscopic management of gastric, duodenal and rectal NETs: Position paper from the Italian Association for Neuroendocrine Tumors (Itanet), Italian Society of Gastroenterology (SIGE), Italian Society of Digestive Endoscopy (SIED)

The present paper reflects the position of the Italian Association for Neuroendocrine Tumors (Itanet), the Italian Society of Gastroenterology (SIGE), and the Italian Society of Digestive Endoscopy (SIED) regarding the management of patients affected by gastric, duodenal, and rectal neuroendocrine neoplasms (NENs) amenable to endoscopic treatment. The key questions discussed in this paper are summarized in Table 1. Data were extracted from the MEDLINE database through searches; expert opinions and recommendations are provided in accordance with the available scientific evidence and the authors' expertise. Recommendations are presented alongside a level of evidence and grade of recommendation based on the GRADE system. This paper specifically focuses on subgroups of NENs considered suitable for endoscopic management according to current international guidelines: i. well-differentiated gastric neuroendocrine tumors (gNET) type 1 < 2 cm and selected cases of type 3; ii. well-differentiated duodenal, non-functioning, non-ampullary NET with size < 2 cm; and well-differentiated rectal NET with size < 2 cm.

Comparing surgical and endoscopic resection approaches for colorectal neuroendocrine tumors within the diameter range of 10-20mm: an inverse probability weighting analysis based on the SEER database

Background

Currently, the primary treatment modalities for colorectal neuroendocrine tumors (CRNET) with a diameter between 10mm and 20mm are surgical resection (SR) and endoscopic resection (ER). However, it remains unclear which surgical approach yields the greatest survival benefit for patients.

Methods

This study included data from patients diagnosed with CRNET with tumor diameters ranging from 10mm to 20mm between the years 2004 and 2019, obtained from the Surveillance, Epidemiology, and End Results (SEER) database. Patients were categorized into ER and SR groups based on the respective surgical approaches. Inverse probability weighting (IPTW) was employed to mitigate selection bias. Kaplan-Meier analysis and log-rank tests were utilized to estimate overall survival (OS) and cancer-specific survival (CSS). Cox regression analysis (univariate and multivariate) was performed to evaluate potential factors influencing survival.

Results

A total of 292 CRNET patients were included in this study (ER group: 108 individuals, SR group: 184 individuals). Prior to IPTW adjustment, Kaplan-Meier analysis and Cox proportional hazard regression analysis demonstrated that the OS and CSS of the SR group were inferior to those of the ER group. However, after IPTW adjustment, no statistically significant differences in prognosis were observed between the two groups. Subgroup analyses revealed that patients with muscular invasion, positive lymph nodes, or distant metastasis derived greater survival benefits from SR. Significant differences in OS and CSS between the two groups were also observed across different age groups.

Conclusion

For patients with mucosal-limited lesions and without local lymph node or distant metastasis, ER is the preferred surgical approach. However, for patients with muscular invasion or positive lymph nodes/distant metastasis, SR offers a better prognosis. The choice of surgical approach should be based on the specific clinical characteristics of patients within different subgroups.

Risk of metastasis and survival in patients undergoing different treatment strategies with T1 colonic neuroendocrine tumors

PURPOSE

The efficacy and safety of local excision (LE) for small (< 1‒2 cm) colonic neuroendocrine tumors (NETs) is controversial due to the higher metastasis risk when compared with rectal NETs. The study aimed to evaluate the metastasis risk of T1 colonic NETs and compare patients' long-term prognosis after LE or radical surgery (RS).

METHODS

The Surveillance Epidemiology and End Results database was used to identify patients with T1 colonic NETs (2004‒2015). Multivariable logistic regression was performed to assess factors associated with metastasis risk. Propensity score matching was used to balance the variables. Cancer-specific survival (CSS) and overall survival (OS) were calculated to estimate the prognosis of patients with T1N0M0 colonic NETs who underwent LE or RS.

RESULTS

Of the 610 patients with colonic NETs, 46 (7.54%) had metastasis at diagnosis. Tumor size (11-20 mm) (OR = 9.51; 95% confidence interval (CI): 4.32‒21.45; P < 0.001), right colon (OR = 15.79; 95% CI 7.20‒38.56; P < 0.001), submucosal infiltration (OR = 2.08; 95% CI 0.84‒5.57; P = 0.125) were independent risk factors associated with metastasis. Of the 515 patients with T1N0M0 colonic NETs, the overall long-term prognosis of LE was as good as that of RS groups (after matching, 5-year CSS: 97.9% vs. 94.6%, P = 0.450; 5-year OS: 92.7% vs. 85.6%, P = 0.009).

CONCLUSION

Tumor size (11‒20 mm) and site (right colon) are associated with metastasis in T1 colonic NETs. In the absence of metastasis, LE could be a viable option for 0‒10 mm T1 colonic NETs with well/moderate differentiation in the left colon in terms of long-term survival.

Endoscopic treatments for rectal neuroendocrine tumors: a systematic review and network meta-analysis

BACKGROUND

Conventional endoscopic mucosal resection (cEMR), EMR with a transparent cap, EMR using a ligation device (EMR-L), EMR after circumferential precutting (EMR-P), and endoscopic submucosal dissection (ESD) have been used for resecting rectal neuroendocrine tumors (r-NETs). However, there is no consensus regarding which is the best treatment. This study aimed to compare the outcomes of the aforementioned 5 techniques for resecting r-NETs by network meta-analysis.

METHODS

Electronic databases (PubMed, Cochrane Library, Embase, Ovid Medline, and Web of Science) were systematically searched to include relevant studies published from inception to September 1, 2023. The en bloc resection rate, histologic complete resection rate, positive lateral margin rate, positive vertical margin rate, adverse events rate, and procedure time were compared.

RESULTS

A total of 27 studies with a total of 2112 r-NETs were included, and the mean diameter of tumors was 6.24 mm. Pairwise meta-analysis showed that EMR-L and ESD had higher en bloc resection and histologic complete resection rates and lower positive vertical margin rate than those of cEMR in resecting r-NETs. Compared with ESD, EMR-L and EMR-P achieved similar resection rates and significantly shortened the procedure time without increasing adverse events. The network meta-analysis evaluated the surface under the cumulative ranking curves and revealed that EMR-L was the best modality for treating r-NETs considering the comprehensive results of the en bloc resection rate, histologic complete resection rate, positive lateral margin rate, positive vertical margin rate, adverse events rate, and procedure time.

CONCLUSION

EMR-L should be recommended as the first-line endoscopic treatment for small r-NETs.

Therapeutic Challenges for Gastric Neuroendocrine Neoplasms: Take It or Leave It?

Background and Objectives: Gastric neuroendocrine neoplasms (gNENs) represent rare but increasingly recognized tumors. They are distinguished into three main clinical types (type-1, type-2, and type-3) according to gastrin level and at histological evaluation in well-differentiated G1, G2, or G3 lesions, as well as poorly-differentiated lesions. Small type-1 and type-2 neoplasms with low proliferation indices demonstrated excellent survival without progression during an extended follow-up period, and for these reasons, active endoscopic observation or endoscopic resection are feasible options. On the other hand, surgery is the treatment of choice for more aggressive type-3, G3, or infiltrating neoplasms. The present study aims to comprehensively review and compare the available therapeutic strategies for gNENs. Materials and Methods: A computerized literature search was performed using relevant keywords to identify all of the pertinent articles with particular attention to gNEN endoscopic treatment. Results: In recent years, different endoscopic resective techniques (such as endoscopic mucosal dissection, modified endoscopic mucosal resection, and endoscopic full-thickness resection) have been developed, showing a high rate of complete resection for advanced and more aggressive lesions. Conclusions: Overall, gNENs represent a heterogeneous group of lesions with varying behavior which require personalized management. The non-operative approach for small type-1 gNENs seems to be feasible and should be promoted. A step-up approach with minimally invasive endoscopic therapies might be proposed, particularly for type-1 gNEN. On the other hand, it is important to recognize the negative prognostic factors in order to identify those rare cases requiring more aggressive approaches. A possible therapeutic algorithm for localized gNEN management is provided.

Risk of second primary cancers in patients with rectal neuroendocrine neoplasms: a surveillance, epidemiology, and end results analysis

Background

While an elevated risk of second primary cancers (SPCs) has been observed in many other cancers, risk of SPCs has not been quantified in patients with rectal neuroendocrine neoplasms (NENs).

Methods

Survivors of primary rectal NENs diagnosed between 2000 and 2018 were identified from the Surveillance, Epidemiology, and End Results (SEER)-18 registries. Relative risk of SPCs was estimated as the standardized incidence ratio (SIR), which was calculated using SEER*Stat software.

Results

Between 2000 and 2018, a total of 15836 patients diagnosed with rectal NENs, of whom 1436 (9.1%) received diagnosis of SPCs (SIR: 1.19, 95%CI: 1.13-1.26). The majority of patients were aged 50-69 and had their first cancer diagnosed at the localized stage. Male survivors had a higher propensity for developing SPCs overall, while female survivors exhibited higher risks of specific SPCs. Age at diagnosis of rectal NENs influenced the risk of SPCs, with younger patients having greater risks. A statistically significant increase in the incidence of SPCs was observed among patients aged 30-64 years. Black patients had higher relative risks of certain SPCs, while White patients had a lower risk of subsequent melanoma. Trend analysis revealed that the highest excess burden of SPCs was observed in the years 2000 to 2002. Risk of SPCs remained elevated within the first four years post-diagnosis for survivors of rectal NENs, but diminished thereafter.

Conclusion

The study revealed that individuals who survived rectal NENs were at an elevated risk of developing SPCs compared to the general population. Our results hold important implications for the formulation of lifelong surveillance recommendations for cancer survivors.

Role of Advanced Gastrointestinal Endoscopy in the Comprehensive Management of Neuroendocrine Neoplasms

Neuroendocrine neoplasms (NENs), also called neuroendocrine tumors (NETs), are relatively uncommon, heterogenous tumors primarily originating in the gastrointestinal tract. With the improvement in technology and increasing use of cross-sectional imaging and endoscopy, they are being discovered with increasing frequency. Although traditionally considered indolent tumors with good prognoses, some NENs exhibit aggressive behavior. Timely diagnosis, risk stratification, and management can often be a challenge. In general, small NENs without local invasion or lymphovascular involvement can often be managed using minimally invasive advanced endoscopic techniques, while larger lesions and those with evidence of lymphovascular invasion require surgery, systemic therapy, or a combination thereof. Ideal management requires a comprehensive and accurate understanding of the stage and grade of the tumor. With the recent advancements, a therapeutic advanced endoscopist can play a pivotal role in diagnosing, staging, and managing this rare condition. High-definition white light imaging and digital image enhancing technologies like narrow band imaging (NBI) in the newer endoscopes have improved the diagnostic accuracy of traditional endoscopy. The refinement of endoscopic ultrasound (EUS) over the past decade has revolutionized the role of endoscopy in diagnosing and managing various pathologies, including NENs. In addition to EUS-directed diagnostic biopsies, it also offers the ability to precisely assess the depth of invasion and lymphovascular involvement and thus stage NENs accurately. EUS-directed locoregional ablative therapies are increasingly recognized as highly effective, minimally invasive treatment modalities for NENs, particularly pancreatic NENs. Advanced endoscopic resection techniques like endoscopic submucosal dissection (ESD), endoscopic submucosal resection (EMR), and endoscopic full-thickness resection (EFTR) have been increasingly used over the past decade with excellent results in achieving curative resection of various early-stage gastrointestinal luminal lesions including NENs. In this article, we aim to delineate NENs of the different segments of the gastrointestinal (GI) tract (esophagus, gastric, pancreatic, and small and large intestine) and their management with emphasis on the endoscopic management of these tumors.

Efficacy of Endoscopic Resection for Rectal Neuroendocrine Tumors Smaller than 15 mm

BACKGROUND

Local resection, including endoscopic resection, is recommended for rectal neuroendocrine tumors (NETs) < 15 mm in patients without risk factors for metastasis, though the short- and long-term outcomes are unclear.

AIMS

This study investigates the efficacy of endoscopic resection for rectal NETs < 15 mm.

METHODS

The short- and long-term outcomes of patients with rectal NETs < 15 mm who underwent endoscopic resection and the outcomes of each endoscopic technique were analyzed. The tumors were stratified as < 10 mm (small-size group, SSG) and 10-14 mm (intermediate-size group, IMG).

RESULTS

Overall, 139 lesions (SSG, n = 118; IMG, n = 21) were analyzed. All tumors were classified as G1 (n = 135) or G2 (n = 4) according to the 2019 World Health Organization grading criteria. The complete resection rate was not different between the groups (P = 0.151). Endoscopic submucosal dissection (ESD) and endoscopic submucosal resection with a ligation device (ESMR-L) achieved complete resection rates > 90% in the SSG. The ESMR-L procedure time (P < 0.001) and hospitalized period (P < 0.001) were significantly shorter than those of ESD. ESD achieved a complete resection rate of 80.0% in the IMG. The tumor size did not affect the overall survival or rate of lymph node/distant metastases.

CONCLUSIONS

Endoscopic resection is a feasible and effective treatment for patients with rectal NETs < 15 mm without the risk factors of metastasis. ESMR-L and ESD are optimal techniques for resecting tumors smaller than 10 mm and 10-14 mm, respectively.

Multiple distant metastases arising from a single, low-grade rectal neuroendocrine tumor: an autopsy case report

BACKGROUND

Rectal neuroendocrine neoplasms are rare epithelial neoplasms of the rectum. The incidence of these tumors has increased over the past decades. However, many questions remain unanswered regarding their clinicopathology, including the possible mechanisms in which these tumors may grow and metastasize.

CASE PRESENTATION

In this case report, we report the findings of an autopsy of a 65-year-old Japanese woman diagnosed with multiple liver metastases from a single, low-grade rectal neuroendocrine tumor. The diagnosis was made in late 2018 to early 2019, and subsequently the patient underwent several rounds of standard chemotherapy. However, due to unfavorable side effects, she opted for palliative care at our hospital instead from December 2020. The patient's condition was generally stable for the next 17 months, but in May 2022, she was hospitalized for increased abdominal pain. Despite enhanced pain control therapy, she eventually passed away. An autopsy was conducted to determine the exact cause of death. The primary rectal tumor was found to be small, but showed strong histological evidence of venous invasion. Metastases in the liver, pancreas, thyroid gland, adrenal glands, and vertebrae were also present. On the basis of the histological evidence obtained, we deduced that the tumor cells may have mutated and gained multiclonality as they spread vascularly to the liver, contributing to the distant metastases.

CONCLUSIONS

The results from this autopsy may provide an explanation for the possible mechanism by which small, low-grade rectal neuroendocrine tumors metastasize.

Endoscopic techniques for gastric neuroendocrine tumors: An update

Gastric neuroendocrine neoplasms (gNENs) are a rare type of gastric neoplasm, even if their frequency is increasing according to the latest epidemiologic revisions of the main registries worldwide. They are divided into three main subtypes, with different pathogeneses, biological behaviors, and clinical characteristics. GNEN heterogeneity poses challenges, therefore these neoplasms require different management strategies. Update the knowledge on the endoscopic treatment options to manage g-NENs. This manuscript is a narrative review of the literature. In recent years, many advances have been made not only in the knowledge of both the pathogenesis and the molecular profiling of gNENs but also in the endoscopic expertise towards innovative treatment options, which proved to be less aggressive without losing the capability of being radical. The endoscopic approach is increasingly applied in the field of gastrointestinal (GI) luminal neoplasms, and this is true not only for adenocarcinomas but also for gNENs. In particular, different techniques have been described for the endoscopic removal of suspected lesions, ranging from classical polypectomy (cold or hot snare) to endoscopic mucosal resection (both with “en bloc” or piecemeal technique), endoscopic submucosal dissection, and endoscopic full-thickness resection. GNENs comprise different subtypes of neoplasms with distinct management and prognosis. New endoscopic techniques offer a wide variety of approaches for GI localized neoplasms, which demonstrated to be appropriate and effective also in the case of gNENs. Correct evaluation of size, site, morphology, and clinical context allows the choice of tailored therapy in order to guarantee a definitive treatment.

Multiple ligation-assisted endoscopic submucosal resection combined with endoscopic ultrasonography: a novel method to treat rectal neuroendocrine tumors

OBJECTIVE

The first choice of treatment for rectal neuroendocrine tumors (R-NETs) 10 mm in size is endoscopic resection, there is still controversy concerning the optimal endoscopic treatment for resecting R-NETs. This study evaluated the efficacy and safety of multiple ligation-assisted endoscopic submucosal resection combined with endoscopic ultrasonography (EMR-MLUS) for R-NETs.

METHODS

We retrospectively analyzed the data of 62 patients with R-NETs ≤10 mm in size who underwent EMR-MLUS or ligation-assisted endoscopic submucosal resection combined with endoscopic ultrasonography (EMR-LUS) between May 2019 and April 2022, including tumor characteristics, endoscopic complete resection, pathological complete resection, the procedure time, adverse events, and follow-up were compared between the two groups of patients.

RESULTS

Of the 62 patients, 19 underwent EMR-MLUS and 43 underwent EMR-LUS. The endoscopic morphology of lesions was statistically different between group EMR-MLUS and group EMR-LUS ( P = 0.015), and most of them were flat and slightly raised lesions in group EMR-MLUS. Although the pathological complete resection rate was slightly higher in the EMR-MLUS group than in the EMR-LUS group (94.74% vs. 90.70%; P = 0.290), the endoscopic complete resection rate was high in both groups. Involvement of the lateral resection margin was found four cases in the ESMR-LUS group; one case of deep resection margin involvement in the EMR-MLUS group. The mean procedure time was longer in the EMR-MLUS group than in the EMR-LUS group (12.79 ± 1.01 min vs. 11.08 ± 1.89 min; P = 0.041). In group EMR-LUS, there were two cases of immediate bleeding; in group EMR-MLUS, one case of perforation, all of them were successfully treated by endoscopy. No recurrence, progression, or metastasis was found in all patients.

CONCLUSION

EMR-MLUS is a safe and effective technique that could be considered when removing small rectal NETs, especially flat and slightly raised lesions.

Multiple rectal neuroendocrine tumors: An analysis of 15 cases and literature review

Multiple neuroendocrine tumors (M-NETs) are rare in the rectum and there is no consensus on their characteristics and treatments. Here, we report 15 cases of rectal M-NETs and review the previous literature. We discuss the clinical characteristics, endoscopic features and pathological features of rectal M-NETs, aiming to analyze the treatments and follow-up strategies in combination with these characteristics. We retrospectively reviewed and analyzed the data of 15 patients with rectal M-NETs who were diagnosed and treated at Beijing Friendship Hospital, Capital Medical University. Their clinical data, endoscopic findings, pathological features and treatments were analyzed. Follow-up evaluations and literature review were performed. In all, 14 male (93.3%) and 1 female (6.7%) were recruited. The average age at diagnosis was 55.7 years. The clinical manifestations include asymptomatic in 9 patients (60.0%), defecation habits changes in 2 patients (13.3%), anal distension in 2 patients (13.3%), and abdominal distension in 2 patient (13.3%). The largest tumor diameter ≤10mm was found in 13 patients (86.7%) and >10mm in 2 patients (13.3%). All of the lesions originated from the mucous or submucosa layer. WHO grades were all NET G1. The number of tumors diagnosed by pathology in 13 patients was consistent with that observed by endoscopy, while more lesions were observed by pathology than endoscopy in two patients. Lymph node metastasis occurred in 1 patient (6.7%), and vascular or lymphatic invasion occurred in 9 patients (60.0%). Among the 13 patients with the largest tumor diameter being ≤10mm, lymphovascular invasion occurred in 8 patients (61.5%). And among the 2 patients with the largest tumor diameter of >10mm, lymphovascular invasion occurred in 1 patient (50.0%). 14 patients underwent endoscopic resection and 1 underwent surgical excision. Postoperative follow-up was achieved in 13 patients and no recurrence or metastasis was found. The true number of rectal M-NETs may be more than seen under endoscopy. Rectal M-NETs is associated with a high risk of metastasis; therefore, treatment and surveillance strategies should be more radical than single lesion.

Comparison of the efficacy of endoscopic submucosal dissection and transanal endoscopic microsurgery in the treatment of rectal neuroendocrine tumors ≤ 2 cm

INTRODUCTION

Currently, complete tumor resection is considered the most effective treatment for rectal neuroendocrine tumors (NETs). Endoscopic submucosal dissection (ESD) and transanal endoscopic microsurgery (TEM) are recommended for rectalNETs ≤2 cm, but it is not clear which method is better. Thus, we evaluated the efficacy of ESD and TEM in the treatment of rectal neuroendocrine tumors (NETs) ≤ 2 cm.

METHODS

We conducted a single-centre retrospective cohort study between 2010 and 2021 of rectal NETs ≤ 2 cm in 114 patients with long-term follow-up data who were divided into ESD (n=55) and TEM groups (n=59). Our study assessed differences between groups in the complete resection rate of lesions, recurrence rate, surgical complications, procedure time, and length of hospital stay.

RESULTS

The co-primary outcomes were the complete resection rate of lesions and the recurrence rate. Compared to that in the ESD group, the complete resection rate was significantly higher in the TEM group (91.5% vs. 70.9%, p=0.005). The median follow-up time was 22 months in our study, and the follow-up outcomes suggested that the rates of recurrence were 1.8% (1/55) and 6.8% (4/59) in the ESD and TEM groups, respectively, with no significant difference between the two groups. The secondary outcomes of the evaluation were surgical complications, procedural time, and length of hospital stay. The rate of complications (gastrointestinal bleeding and perforation) was low in both the ESD (7.3%, 4/55) and TEM (5.1%, 3/59) groups. No difference in hospitalization duration was observed between the two groups in our study. However, the procedure time was significantly shorter in the ESD group than in the TEM group (27.5 min vs. 56 min, p<0.001).

CONCLUSIONS

Although the rate of complete resection in the TEM group was higher than that in the ESD group, there was no difference in recurrence rates between the two modalities during long-term follow-up. Depending on the qualities of the available hospital resources in the area, one of the two approaches can be adopted.