Oncological outcomes according to the treatment modality based on the size of rectal neuroendocrine tumors: a single-center retrospective study

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.

Assessing risk stratification in long-term outcomes of rectal neuroendocrine tumors following endoscopic resection: a multicenter retrospective study

OBJECTIVES

While endoscopic resection of rectal neuroendocrine tumors (NETs) has significantly increased, long-term data on risk factors for recurrence are still lacking. Our aim is to analyze the long-term outcomes of patients with rectal NETs after endoscopic resection through risk stratification.

METHODS

In this multicenter retrospective study, we included patients who underwent endoscopic resection of rectal NETs from 2009 to 2018 and were followed for ≥12 months at five university hospitals. We classified the patients into three risk groups according to the clinicopathological status of the rectal neuroendocrine tumors: low, indeterminate, and high. The high-risk group was defined if the tumors have any of the followings: size ≥ 10 mm, lymphovascular invasion, muscularis propria or deeper invasion, positive resection margins, or mitotic count ≥2/10.

RESULTS

A total of 346 patients were included, with 144 (41.6%), 121 (35.0%), and 81 (23.4%) classified into the low-, indeterminate-, and high-risk groups, respectively. Among the high-risk group, seven patients (8.6%) received salvage treatment 28 (27-67) days after the initial endoscopic resection, with no reported extracolonic recurrence. Throughout the follow-up period, 1.1% (4/346) of patients experienced extracolonic recurrences at 56.5 (54-73) months after the initial endoscopic resection. Three of these patients (75%) were in the high-risk group and did not undergo salvage treatment. The risk of extracolonic recurrence was significantly higher in the high-risk group compared to the other groups (p = 0.039).

CONCLUSION

Physicians should be concerned about the possibility of metastasis during long-term follow-up of high-risk patients and consider salvage treatment.

Risk Factor Analysis of Lymph Node Metastasis for Rectal Neuroendocrine Tumors: Who Needs a Radical Resection in Rectal Neuroendocrine Tumors Sized 1-2 cm?

BACKGROUND

Rectal neuroendocrine tumors (NETs) have malignant potential, and lymph node (LN) or distant metastases can occur; however, treatment of NETs 1-2 cm in size is controversial.

OBJECTIVE

This study aimed to identify predictive factors for LN metastasis and prognostic factors for recurrence of rectal NETs, especially tumors 1‒2 cm in size.

METHODS

Between October 2004 and November 2020, 453 patients underwent endoscopic or surgical treatment for rectal NETs in Seoul National University Hospital. The data on these patients were prospectively collected in our database and reviewed retrospectively. In cases of local excision, we evaluated LN metastasis with radiologic imaging, including computed tomography or magnetic resonance imaging before treatment and during the follow-up periods.

RESULTS

LN metastasis was observed in 40 patients (8.8%). A higher rate of LN metastasis was observed in larger-sized tumors, advanced T stage, lymphovascular invasion (LVI), perineural invasion (PNI), and high tumor grade. In multivariable analysis, the significant risk factors for LN metastasis were tumor size (1 ≤ size < 2 cm: hazard ratio [HR] 64.07; size ≥2 cm: HR 102.37, p < 0.001) and tumor grade (G2: HR 3.63, p = 0.034; G3: HR 5.09, p = 0.044). In multivariable analysis for tumors 1-2 cm in size, the risk factor for LN metastasis was tumor grade (G2: HR 6.34, p = 0.013).

CONCLUSIONS

Tumor grade and size are important predictive factors for LN metastasis. In NETs 2 cm in size, tumor grade is also important for LN metastasis, and radical resection should be considered.

Endoscopic mucosal resection using anchored snare Tip-in versus precut technique for small rectal neuroendocrine tumors

BACKGROUND/AIMS

Small rectal neuroendocrine tumors (NETs) can be treated with modified endoscopic mucosal resection (EMR). However, an optimal EMR method remains to be established. We aimed to assess the non-inferiority of Tip-in EMR versus precut EMR (EMR-P) for treating rectal NETs.

METHODS

This prospective, multicenter, randomized controlled trial enrolled patients with rectal NETs of < 10 mm in diameter. The patients were randomly assigned to EMR-P and Tip-in EMR groups in a 1:1 ratio. Primary outcome was margin-negative (R0) resection rate between the two methods, with a noninferiority margin of 10%.

RESULTS

Seventy-five NETs in 73 patients, including 64 eligible lesions (32 lesions in each, EMR-P and Tip-in EMR groups), were evaluated. In a modified intention-to-treat analysis, R0 resection rates of the EMR-P and Tip-in EMR groups were 96.9% and 90.6%, respectively, which did not demonstrate non-inferiority (risk difference, -6.3 [95% confidence interval: -18.0 to 5.5]). Resection time in the EMR-P group was longer than that in the Tip-in EMR group (p < 0.001). One case of intraprocedural bleeding was reported in each group.

CONCLUSION

We did not demonstrate the non-inferiority of Tip-in EMR compared to EMR-P for treating small rectal NETs. However, the R0 resection rates for both techniques were high enough for clinical application.

Current status of the role of endoscopy in evaluation and management of gastrointestinal and pancreatic neuroendocrine tumors

The incidence of gastroenteropancreatic neuroendocrine tumors (GEP-NETs) has increased over the last several decades. In general, NETs are slow-growing neoplasms and the data on the natural history is still evolving. The availability and improved utilization of advanced imaging modalities have allowed the selection of cases suitable for endotherapy. In this regard, endoscopic ultrasound (EUS) has emerged as a central imaging modality to assess the depth of infiltration in gastroduodenal as well as rectal NETs. Enhanced EUS modalities, including contrast-enhanced EUS and EUS elastography, reliably differentiate pancreatic neuroendocrine tumors (PNETs) from adenocarcinomas and may enable prediction of aggressive PNETs. With recent developments in therapeutic endoscopy, a large proportion of GEP-NETs can be safely managed endoscopically. Endoscopic resection techniques, including endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD), allow the safe removal of gastroduodenal and rectal NETs. Recent data indicate that modified EMR techniques may be superior to conventional EMR with regard to histologically complete resection. Device-assisted endoscopic full thickness resection is emerging as a safe and effective technique for upper gastrointestinal as well as rectal NETs. In selected cases with PNETs, who are otherwise unfit for surgery, EUS-guided ablation is increasingly being recognized as a safe treatment option. This review focusses on evidence-based approaches to endoscopic evaluation and the management of GEP-NETs with special emphasis on recent advancements.

Clinical outcomes and risk factors associated with poor prognosis after endoscopic resection of 10-20 mm rectal neuroendocrine tumors: a multicenter, retrospective study of 10-year experience

BACKGROUND

The efficacy of endoscopic resection for of 10-20 mm rectal neuroendocrine tumor (NET) remains controversial. We aimed to evaluate the clinical outcomes and risk factors associated with poor prognosis after endoscopic resection of 10-20 mm rectal NET and to determine the optimal treatment.

METHODS

Patients who underwent endoscopic resection for rectal NET in four tertiary hospitals were enrolled, and data on with the clinical outcomes and risk factors related to poor prognosis were retrospectively analyzed.

RESULTS

A total of 105 patients who underwent endoscopic submucosal resection (ESD; n = 65, 61.9%), modified endoscopic mucosal resection (mEMR; n = 31, 29.5%), and conventional EMR (cEMR; n = 9, 8.6%) were enrolled. The mean follow-up period was 41.2 ± 21.9 months. In the morphologic findings, the mean diameter was 11.6 mm (range 10-19); the shape was sessile (50.5%) and mixed type (49.5%), and surface depression was observed in 41.9% of patients. In the histologic findings, 87.6% of patients had G1 and 12.4% G2 tumor grade, and 3.8% of patients had lymphovascular invasion. The overall en bloc and histologically complete (R0) resections were 99.1% and 76.2%, respectively. cEMR was a less-frequently developed R0 resection. In the univariate and multivariate analyses for R0 resection, only surface depression was significantly associated. Regional or distant organs metastasis during follow-up developed in three patients (2.9%) and was significantly associated with female sex, redness, G2 tumor grade, and non-ESD methods.

CONCLUSION

Patients who underwent endoscopic resection of 10-20 mm rectal NET had good prognosis; therefore, endoscopic resection can be considered as the first-line treatment, particularly for 10-14 mm rectal NET. However, the risk factors, such as female sex, redness, G2 tumor grade and non-ESD methods, were associated with regional or distant metastases during follow-up. Therefore, patients with these risk factors should be carefully monitored.

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.

Rectal Neuroendocrine Neoplasms: Why Is There a Global Variation?

Purpose of Review

This review examines the variation in incidence of rectal neuroendocrine tumours across the globe. Rectal neuroendocrine tumours are a common type of gastrointestinal NET with an increasing incidence reported over the last 30 years.

Recent Findings

There have been a number of publications examining the epidemiology of neuroendocrine tumours across the world. These have utilized a variety of different methodologies to examine both incidence of prevalence of NETs. We review the data published and describe any causative factors and findings regarding the epidemiology of rectal NETs.

Summary

Rectal NETs account for 1–2% of all rectal cancers and are commonly diagnosed between 50–60 years of age. Most lesions are identified by chance at colonoscopy, commonly during colon cancer screening procedures, which is reflected in part in the age at diagnosis. Most lesions are small in size, < 10 mm and can be managed with endoscopic resection rather than requiring surgery. The highest incidence is reported in people of Asian ethnicity, with a tenfold increased incidence reported in some series compared with white population. There is also an increased incidence in Black and Hispanic population as identified through the Surveillance, Epidemiology and End Results (SEER) database. Endoscopic assessment of lesions is variable globally. Future work to better understand the cause of ethnic variation and development of comprehensive cancer registries would be helpful.

Implementation of robot-assisted curative resection for rare anorectal tumours on the basis of individualised treatment

PURPOSE

To evaluate the validity of robot-assisted curative operation for rare anorectal tumours, characterised by biological heterogeneity and anatomical complexity.

METHODS

The present study evaluated 16 consecutive patients including three with anorectal squamous cell carcinoma (ARSCC), four with anorectal mucosal melanoma (ARMM), seven with anorectal neuroendocrine tumour (ARNET), and two with other types of anorectal tumours.

RESULTS

Of the three patients with ARSCC after chemoradiotherapy, two underwent abdominoperineal resection (APR), and one underwent ultralow anterior resection (uLAR)/total intersphincteric resection (ISR), surviving 56-76 months without recurrence. Of the four ARMM patients, APR and uLAR/total ISR were conducted in two patients, respectively, with variable survival outcomes. All seven patients with ARNET were treated with uLAR/ISR and LAR, surviving for 5-106 months to date.

CONCLUSIONS

Because most anorectal tumours are confined to the dermal and submucosal layers, robotic anorectal function preserving ISR is expected to achieve R0 resection.

Comparable survival benefit of local excision versus radical resection for 10- to 20-mm rectal neuroendocrine tumors

OBJECTIVE

The optimal surgical management for 10- to 20-mm rectal neuroendocrine tumors (RNET) is still a matter of debate. This study aimed to explore the optimal surgical approach for 10- to 20-mm RNET by comparing the outcomes between local excision and radical resection.

METHOD

We extracted clinicopathological information of 10- to 20-mm RNET from the Surveillance, Epidemiology, and End Results (SEER) database. The 1:2 propensity score matching (PSM) method was used to balance the imbalanced baseline covariates (P < 0.05) between the local excision group and radical resection group. A Cox proportional hazards model was used to identify the risk factors associated with cancer-specific survival (CSS) and overall survival (OS).

RESULT

A total of 531 RNET patients 10-20 mm in size were included. Patients receiving radical resection had larger tumor sizes (P < 0.001), higher T stages (P < 0.001), higher N stages (P < 0.001), higher M stages (P = 0.002) and higher grades (P = 0.041). For 10-20 mm RNET patients, radical resection had no survival benefit compared with local excision (CSS: HR = 2.048, 95% CI 0.553-7.576, P = 0.283; OS: HR = 1.090, 95% CI 0.535-2.219, P = 0.813). After 1:2 PSM, there was no significant difference between local excision and radical resection. Radical resection still had no survival benefit over local excision (CSS: HR = 0.449, 95% CI 0.050-4.022, P = 0.474; OS: HR = 1.408, 95% CI 0.488-4.061, P = 0.527). In a multivariate analysis of CSS, age >60 years old (P = 0.005), tumour size 14-20 mm (P = 0.011) and M1 stage (P < 0.001) were identified as independent prognostic factors for worse CSS. In multivariate analysis of OS, age>60 years (P＜0.001), male sex (P = 0.007), black race (P = 0.016), and T2/T3/T4 stage (P = 0.007) were significantly associated with worse OS. N stage was not an independent predictive factor for CSS and OS.

CONCLUSION

This study revealed that for 10- to 20-mm RNET patients, there was no survival benefit for radical resection compared with local excision, which suggested that local excision may be an adequate treatment for these patients.