Rectal Neuroendocrine Tumors Research Articles

An Update on the Management of Rectal Neuroendocrine Neoplasms.

Rectal neuroendocrine neoplasms (NENs) are increasing in incidence. Most lesions are low grade, well-differentiated neuroendocrine tumours with good long term outcomes. However there is metastatic potential and resection offers the only option for a cure and in most cases should be offered to reduce the risk of metastases. Careful staging of rectal NENs should be performed prior to consideration of resection in order to ensure the appropriate technique is chosen, and reduce the risk of incomplete resection. Resection can be endoscopic or surgical, and selecting the appropriate resection technique relies on tumour characteristics such as size, grade, invasion into the muscularis propria, presence of lymph node involvement or of distal metastases. Some patients may require systemic therapies which may involve somatostatin analogues (SSAs), everolimus, tyrosine kinase inhibitors (TKIs), chemotherapy or peptide receptor radionuclide therapy (PRRT). Due the rarity of these tumours, much of the evidence is based on retrospective reviews or smaller cohort studies. This article is an update of the current evidence available to guide management.

A Comprehensive Review on Recent Advances in Management, Presentation, and Pathophysiology of Rectal Neuroendocrine Tumors

A Comprehensive Review on Recent Advances in Management, Presentation, and Pathophysiology of Rectal Neuroendocrine Tumors

Optimization of endoscopic treatment strategies for R0 resection of rectal neuroendocrine tumors smaller than 10 mm

BackgroundThe optimal histologically complete (R0) resection methods of endoscopy for rectal neuroendocrine tumor (NET) ≤ 10 mm remains controversial. We aimed to assess the optimal endoscopic treatments for NETs. MethodsThe retrospective enrolled patients (n = 208) with rectal NETs were divided into 3 subsets according to pathological tumor size: 2 - 3 mm, 4 - 5 mm, and 6 - 10 mm NETs. Factors associated with R0 resection according to different endoscopic treatments (accidental diagnostic biopsy by cold forceps, endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD)) and tumor size were investigated. All patients underwent follow-up and no local recurrence or metastasis were identified. ResultsA total of 208 patients were enrolled. In patients with 2 - 3 mm NETs, the R0 resection rate was 100.0 % for biopsy, EMR, and ESD. The R0 resection rate for biopsy of 4 - 5 mm and 6 - 10 mm NETs was 34.3 % and 0.0 % respectively, which was inferior to the EMR/ESD rate (4 - 5mm: p < 0.001; 6 - 10 mm: p < 0.001: respectively). For patients with ≤ 10 mm NETs, EMR and ESD had a comparable en bloc (p = 0.082) and R0 resection rates (p = 0.651). ConclusionAccidental diagnostic biopsy by cold forceps could be considered as the possible treatment for 2 - 3 mm rectal NETs. And for patients with ≤ 10 mm rectal NETs, both EMR and ESD might be sufficient.

Conventional versus rubber band traction-assisted endoscopic submucosal dissection for rectal neuroendocrine tumors: a single-center retrospective study (with video)

BackgroundEndoscopic submucosal dissection (ESD) is a safe and effective technique for the treatment of gastrointestinal tumors, including rectal neuroendocrine tumors (r-NETs). However, the relative advantages of traction-assisted ESD for the treatment of small rectal lesions are still debated.AimsWe conducted a study to compare the efficacy and safety of rubber band traction-assisted ESD (RBT-ESD) to conventional ESD (C-ESD).MethodsThis study retrospectively analyzed consecutive patients with r-NET treated with ESD between October 2021 and October 2023. Our study assessed differences between the groups in the complete resection rate of lesions, muscular layer injury, surgical complications, operation time, resection speed, time to liquid diet, postoperative hospital stay, hospital cost, and recurrence rate.ResultsA total of 119 patients with r-NETs participated in this study (RBT-ESD group, n = 27; C-ESD group, n = 92). The operation time in RBT-ESD group was shorter than in C-ESD group, but the difference was not statistically significant (16.0 min [9.0–22.0 min] vs. 18.0 min [13.3–27.0 min], P = 0.056). However, the resection speed was significantly faster in the RBT-ESD group (6.7 vs. 4.1 mm2/min, P = 0.005). Furthermore, the RBT-ESD group showed significantly less muscular layer injury (P = 0.047) and faster diet recovery (P = 0.035). No significant differences were observed in the complete resection rate, surgical complications, postoperative hospital stay, hospital cost, or recurrence rate between the two groups.ConclusionFor r-NETs of < 2 cm in size, the RBT method did not significantly shorten the operation time but resulted in faster resection speed, less muscular layer injury, and earlier postoperative recovery to a liquid diet.Graphical

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

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. 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. 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. 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.

Clinical significance of positive resection margin for patients with rectal neuroendocrine tumors within 20 mm following initial endoscopic resection: A multi-center study

BackgroundThe incidence of rectal neuroendocrine tumors (RNETs) has witnessed a significant surge, with a notable proportion being amenable to endoscopic removal. However, the clinical significance of positive resection margin for RNETs patients following endoscopic resection remain unknown, resulting in a lack of consensus regarding the appropriateness of implementing salvage treatment. MethodsIn this large, multicenter, retrospective cohort study, we analyzed the medical records of individuals who underwent endoscopic resection for RNETs and classified them into two groups: the positive resection margin and the negative resection margin group. The overall survival (OS) and disease-free survival (DFS) were compared among two group. The independent variables were identified using univariate and multivariate logistic regression analyses to predict positive resection margin. Then, the model was established to predict the patients with positive resection margin using multivariate logistic regression. Results181 RNETs patients (34.3 %) represented positive margin after endoscopic resection. Following a median follow-up period of 72 months, tumor recurrence manifested in 12 out of 527 patients (2.2 %) and the presence of positive resection margin was associated with worse DFS. Independent factors correlating with positive resection margin included endoscopic resection method choice, RNETs located in the low rectum, NLR >4.44 and tumor size exceeding 14.89 mm. A prediction model was therefore established with high predictive accuracy and excellent clinical applicability determined by calibration curves and DCA curve. Among RNETs patients with positive margin following endoscopic resection, implementing salvage treatment was beneficial for improving DFS and salvage endoscopic resection offer equal efficiency compared with salvage radical resection. ConclusionsPositive resection margin following endoscopic resection may indicate negative prognosis. Salvage treatment can improve the prognosis of RNETs patients with positive resection margin. Notably, salvage local resection exhibited similar efficacy compared with radical surgery in term of survival benefit.

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

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. 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. 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. 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.

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.

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. This study included 214 patients with rectal NETs who underwent curative surgery. We evaluated their clinicopathological characteristics and short- and long-term outcomes. LPLN dissection was performed in 15 patients with LPLN swelling ≥ 7mm (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 59.4months, 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. 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.

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

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. 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. 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). 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.

Lateral pelvic lymph nodes dissection of rectal neuroendocrine neoplasms: A prospective case-series and literature review

BackgroundRectal neuroendocrine neoplasms are relatively rare. Patients with rectal neuroendocrine neoplasms undergoing radical surgery have a higher rate of lymph node metastases. Robust evidence on the status of lateral pelvic lymph node metastases and the role of lateral pelvic lymph node dissection in those patients is lacking. This case-series study aimed to explore and address these issues. MethodsThis single-center, prospective case series consecutively enrolled patients with biopsy-proven rectal neuroendocrine neoplasms in a tertiary referral hospital between June 2022 and January 2024. All eligible patients underwent laparoscopic total mesorectal excision surgery and bilateral lateral pelvic lymph node dissection under general anesthesia. The clinicopathologic features, surgical outcomes, and postoperative complications were presented. The last follow-up was conducted in March 2024. ResultsA total of 11 patients with rectal neuroendocrine neoplasms—3 female and 8 male—were enrolled. The average age was 60.0 years (range, 53.5–65.5 years), and the median tumor size was 2.0 cm (range, 1.6–2.5 cm). Tumors invaded the muscularis propria in 7 patients. There were 3 cases of neuroendocrine tumor G1, 6 cases of neuroendocrine tumor G2, and 2 cases of neuroendocrine carcinoma. Among these patients, 11 (100.0%) had lymph node metastases, and 6 (54.5%) had lateral pelvic lymph node metastases. In addition, in 2 patients, only lateral pelvic lymph node metastases were observed, without involvement of the mesenteric lymph nodes. Five patients had tumors located on the left wall of the rectum, and only left-sided lateral pelvic lymph node metastases were observed. The other patient had both sides of lateral pelvic lymph node metastases due to circumferential growth of the tumor around the rectum. Anal preservation was achieved in all patients. The median operating time was 235.0 minutes (range, 210.5–335.5 minutes), and the median estimated blood loss was 50.0 mL (range, 45.0–75.0 mL). Two patients experienced postoperative dysuria and recovered spontaneously within 2–4 months after surgery. ConclusionOn the basis of a prospective case series, we demonstrate, for the first time, the lateral pelvic lymph node metastasis status in patients with rectal neuroendocrine neoplasms requiring radical total mesorectal excision surgery. Simultaneous bilateral lateral pelvic lymph node dissection may be a feasible and beneficial procedure for preventing local recurrence in these patients due to the lack of definitive neoadjuvant or adjuvant therapy options.

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

BackgroundOwing 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.MethodsWe 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.ResultsWe 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.ConclusionsLaparoscopic 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.

Distinct clinicopathological features of neuroendocrine liver metastases originating from the pancreas and rectum

IntroductionSurvival comparisons among patients with liver metastases from pancreatic and rectal neuroendocrine tumors (NETs) were limited, and the efficacy of observation rules in patients undergoing hepatectomy for neuroendocrine liver metastases (NELMs) was unknown. This study aims to distinguish these characteristics and clarify the effects of the observation rules on NELMs.MethodsClinical data were separately collected from patients with pancreatic and rectal NELMs at medical centers in both Japan and China. The Japanese cohort followed the observation rules for the resection of NELMs. A comparative analysis was conducted on clinical characteristics and prognosis features such as overall survival time (OS) and disease-free survival interval (DFS-I).ResultsEnrollment included 47 and 34 patients from Japan and China, respectively. Of these, 69 and 12 patients had tumors originating from the pancreas and rectum, respectively. The OS time in patients undergoing primary tumor resection was significantly longer; however, the OS time between the patients undergoing and not undergoing radical resection of liver metastasis was the same. In asynchronous NELMs, patients with rectal (R)-NELMs showed a significantly higher proportion of type III NELMs. Additionally, the median DFS-I of asynchronous R-NELMs was longer than the recommended follow-up time, with 71.4% of them classified as G2. In the Japanese cohort, patients who adhered to the observation rules exhibited a longer median DFS after hepatectomy for NELMs compared with their counterparts.ConclusionAlthough curative surgery is crucial for primary lesions, personalized approaches are required to manage NELMs. Extended overall follow-ups and shortened follow-up intervals are recommended for G2 stage rectal NETs. The observation rules for NELMs require further validation with a larger sample size.

GATIS score for predicting the prognosis of rectal neuroendocrine neoplasms: A Chinese multicenter study of 12-year experience.

There is currently a shortage of accurate, efficient, and precise predictive instruments for rectal neuroendocrine neoplasms (NENs). To develop a predictive model for individuals with rectal NENs (R-NENs) using data from a large cohort. Data from patients with primary R-NENs were retrospectively collected from 17 large-scale referral medical centers in China. Random forest and Cox proportional hazard models were used to identify the risk factors for overall survival and progression-free survival, and two nomograms were constructed. A total of 1408 patients with R-NENs were included. Tumor grade, T stage, tumor size, age, and a prognostic nutritional index were important risk factors for prognosis. The GATIS score was calculated based on these five indicators. For overall survival prediction, the respective C-indexes in the training set were 0.915 (95% confidence interval: 0.866-0.964) for overall survival prediction and 0.908 (95% confidence interval: 0.872-0.944) for progression-free survival prediction. According to decision curve analysis, net benefit of the GATIS score was higher than that of a single factor. The time-dependent area under the receiver operating characteristic curve showed that the predictive power of the GATIS score was higher than that of the TNM stage and pathological grade at all time periods. The GATIS score had a good predictive effect on the prognosis of patients with R-NENs, with efficacy superior to that of the World Health Organization grade and TNM stage.

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

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. 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. 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, 1.64-76.71months), during which only one patient developed local recurrence. 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.

PCSK2 can be Useful in a Panel Approach to Distinguish Foregut and Midgut Neuroendocrine Tumors.

A number of immunohistochemical stains have been examined for utility in establishing the site of origin for metastatic well-differentiated neuroendocrine tumors (NETs). In the gastrointestinal (GI) tract, distinguishing metastatic duodenal NETs from jejunoileal and other GI NETs is important for clinical work-up, prognosis, and therapy. A recent study indicated that prohormone convertase 2 (PCSK2 or PC2) had broad expression in small intestine and appendiceal NETs. Because the study did not include duodenal NETs, we examined PCSK2 expression in duodenal and other GI NETs. GI NETs (n = 69) and 13 corresponding lymph node metastases from stomach, duodenum, pancreas, ileum, appendix, and rectum were evaluated for the expression of PCSK2, along with ISL1, NKX2.2, CDX2, SATB2, and PAX8. Expression of each stain was evaluated using the H-score system, and differences in expression by site were evaluated by the chi square test. PCSK2 was expressed at similar frequency in duodenal (50%), pancreatic (59%), and ileal NETs (40%). PCSK2 was infrequently expressed in stomach (0%), appendiceal (8%), and rectal (25%) NETs. However, incorporating PCSK2 into a panel including ISL1, NKX2.2, CDX2, and SATB2 allowed development of an algorithm which had 87% sensitivity and 93% specificity for classification of ileal NETs; and 68% sensitivity and 98% specificity for pancreaticoduodenal NETs. In contrast to previous findings, PCSK2 does not show specificity for any particular GI site. An algorithmic approach incorporating the expression of PCSK2 with that of ISL1, NKX2.2, CDX2, and SATB2 is useful in discriminating pancreatic, duodenal, ileal, appendiceal, and rectal NETs.

Outcome of Endoscopic Resection of Rectal Neuroendocrine Tumors ≤ 10 mm.

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

Predictors of lymph node metastasis and survival in radically resected rectal neuroendocrine tumors: A Surveillance, Epidemiology, and End Results (SEER) database analysis

BackgroundRectal neuroendocrine tumors are uncommon tumor types. Lymph node metastases may occur in up to 40%, potentially impacting decision-making. We aimed to assess risk factors for lymph node metastases of rectal neuroendocrine tumors and their association with overall and cancer-specific survival. MethodsThis retrospective case–control study involved patients with stage I to III rectal neuroendocrine tumors who underwent radical resection. Data were derived from the Surveillance, Epidemiology, and End Results database (2000–2020). Patients with pathologic evidence of lymph node metastases were compared to those without lymph node metastases for baseline patient and tumor characteristics. The main outcomes were lymph node metastases, overall survival, and cancer-specific survival. ResultsIn total, 580 patients (50.9% male; mean age: 58.9 years) were included. The lymph node metastases rate was 37.1%. Independent predictors of lymph node metastases were Grade 2 neuroendocrine tumors (odds ratio: 8.06; P = .001), neuroendocrine carcinoma (odds ratio: 2.59, P = .006), large-cell neuroendocrine carcinoma (odds ratio: 4.89; P = .017), T2 tumors (odds ratio: 6.44; P < .001), T3 tumors (odds ratio: 27.5; P < .001), and T4 tumors (odds ratio: 17.3; P < .001). Lymph node metastases were associated with shorter restricted mean overall survival (40.8 vs 52.7 months; P < .001) and cancer-specific survival (41.3 vs 54.8 months; P < .001). When adjusted for other confounders, the nodal status of rectal neuroendocrine tumors was not independently associated with overall (hazard ratio = 1.56; P = .165) or cancer-specific survival (hazard ratio = 1.69; P = .158). Significant factors associated with worse overall survival and cancer-specific survival were age, tumor size, neuroendocrine carcinomas, large-cell neuroendocrine carcinomas, and the number of positive lymph nodes. ConclusionsLymph node metastases of rectal neuroendocrine tumors were more likely associated with high-grade, large-sized, and T2 to T4 tumors. The number of involved lymph nodes was an independent predictor of overall and cancer-specific survival. Other independent survival predictors were tumor grade, size, and T stage.

Efficacy of underwater endoscopic intermuscular dissection in the management of a rectal neuroendocrine tumor.

Efficacy of underwater endoscopic intermuscular dissection in the management of a rectal neuroendocrine tumor.

The role of endoscopic ultrasonography for diagnosis of residual rectal neuroendocrine tumor.

Endoscopic ultrasonography (EUS) is useful for assessing the depth and regional lymph node involvement in rectal neuroendocrine tumors (NETs). However, evidence regarding the effectiveness of EUS in identifying residual lesions in patients with incompletely resected NET is limited. We aimed to evaluate the efficacy of EUS in identifying residual rectal NETs and the clinical outcomes of salvage endoscopic treatment. We retrospectively reviewed the records of patients who were transferred to Chosun University Hospital and received salvage treatment for incompletely resected rectal NETs between January 2012 and October 2021. This study included 68 incompletely resected rectal NET, of which 59 were margin-positive and 9 were margin-indeterminate. EUS detection (odds ratio (OR), 8.44; 95% confidence interval (CI), 1.18-41.35) and visual detection (OR, 7.00; 95% CI, 1.50-47.48) were associated with residual lesion in patients with incompletely resected NET. EUS detection of residual lesions showed a sensitivity of 94%, specificity of 71%, positive predictive value of 88%, negative predictive value of 83%, and accuracy of 87%. All patients underwent salvage treatment with band-ligation endoscopic mucosal resection (58.8%) and endoscopic submucosal dissection (41.2%). Residual NETs were diagnosed in 47 of 68 patients (69.1%), and no recurrence was noted during the follow-up period of 51.8 ± 22.9months. EUS is a more sensitive method than visual detection for evaluating residual rectal NETs. Salvage endoscopic treatment for incompletely resected NETs is safe and effective.

Comparative Efficacy and Acceptability of Endoscopic Methods for Rectal Neuroendocrine Neoplasms with Low Malignant Potential: A Network Meta-analysis.

Although endoscopic resection is an effective treatment of rectal neuroendocrine neoplasms (R-NENs) with low malignant potential, there is no consensus on the most recommended endoscopic method. This study aimed to assess the efficacy and acceptability of different endoscopic treatments for R-NENs with low malignant potential. We searched databases for studies on treatments of R-NENs using endoscopic resection. These studies comprised techniques such as endoscopic mucosal resection (EMR), endoscopic submucosal dissection (ESD), modified endoscopic mucosal resection (EMRM), modified endoscopic submucosal dissection (ESDM), and transanal endoscopic microsurgery (TEM). The primary outcomes assessed were histological complete resection (HCR). Overall, 38 retrospective studies (3040 R-NENs) were identified. Endoscopic mucosal resection with a cap (EMRC), endoscopic mucosal resection with ligation (EMRL), ESD, ESDM, and TEM demonstrated higher resectability than did EMR in achieving HCR. Endoscopic mucosal resection, EMRC, EMRL, EMRP, EMRD, and EMRU required shorter operation times than did ESD. Endoscopic mucosal resection, EMRC, ESDM, and TEM incurred lower risks than did ESD. Regarding R-NENs <20 mm with low malignant potential, ESD could be used as the primary treatment. However, TEM may be more effective if supported by economic conditions and hospital facility. With respect to R-NENs <16 mm with low malignant potential, EMRL could be used as the primary treatment. In regard to R-NENs <10 mm with low malignant potential, EMRL, EMRC, and ESD could be used as the primary treatment. However, EMRL and EMRC might be better when operational difficulties and economic conditions were considered.