Predictors of lymph node metastases and impact on survival in resected pancreatic neuroendocrine tumors: a single-center experience

Surface functionalized nanomaterial systems for targeted therapy of endocrine related tumors: a review of recent advancements

The application of multidisciplinary techniques in the management of endocrine-related cancers is crucial for harnessing the advantages of multiple disciplines and their coordinated efforts in eliminating tumors. Due to the malignant characteristics of cancer cells, they possess the capacity to develop resistance to traditional treatments such as chemotherapy and radiotherapy. Nevertheless, despite diligent endeavors to enhance the prediction of outcomes, the overall survival rate for individuals afflicted with endocrine-related malignancy remains quite miserable. Hence, it is imperative to investigate innovative therapy strategies. The latest advancements in therapeutic tactics have offered novel approaches for the therapy of various endocrine tumors. This paper examines the advancements in nano-drug delivery techniques and the utilization of nanomaterials for precise cancer cures through targeted therapy. This review provides a thorough analysis of the potential of combined drug delivery strategies in the treatment of thyroid cancer, adrenal gland tumors, and pancreatic cancer. The objective of this study is to gain a deeper understanding of current therapeutic approaches, stimulate the development of new drug DDS, and improve the effectiveness of treatment for patients with these diseases. The intracellular uptake of pharmaceuticals into cancer cells can be significantly improved through the implantation of synthetic or natural substances into nanoparticles, resulting in a substantial reduction in the development of endocrine malignancies.

Impact of Regional Metastasis on Survival for Patients with Nonfunctional Pancreatic Neuroendocrine Tumors: A Systematic Review

BACKGROUND

Controversy exists regarding the benefit of lymphadenectomy for nonfunctional pancreatic neuroendocrine tumors (NF-PNET).

PATIENTS AND METHODS

MEDLINE/PubMed, EMBASE, and the Cochrane Library were searched for studies of pancreatic neuroendocrine tumors (PNET) published between 1990 and 2021. Studies of functional PNET were excluded. Reported incidence of lymph node metastasis (LNM) and survival analysis of either disease-free survival (DFS) or overall survival (OS) were required for inclusion.

RESULTS

Overall, 52 studies analyzing 24,608 PNET met the inclusion criteria. The reported LNM rate for NF-PNET ranged from 7 to 64 % (median 24.5%). Reported LNM rates ranged from 7 to 51% (median 11%) for NF-PNET< 2 cm in 14 studies and 29-47% (median 38%) in NF-PNET > 2 cm. In total, 19 studies (66%) reported LNM to have a negative impact on DFS. Additionally, 21 studies (60%) reported LNM to have a negative impact on OS. Two studies investigating the impact of lymphadenectomy (LND) found LND had the greatest impact for large, high-grade tumors. The overall quality of available evidence was low as assessed by the Grading of Recommendations, Assessment, Development, and Evaluation System.

CONCLUSIONS

Published literature evaluating the impact of regional LNM and LND in PNET is confounded by heterogeneity in practice patterns and the retrospective nature of these cohort studies. Most studies suggest high rates of LNM in NF-PNET that negatively impact DFS and OS. Given the high rate of LNM in NF-PNET and its potential detrimental effect on DFS and OS, we recommend lymphadenectomy be completed for NF-PNET > 2 cm and strongly considered for NF-PNET < 2 cm.

Accuracy and Prognostic Impact of Nodal Status on Preoperative Imaging for Management of Pancreatic Neuroendocrine Tumors: A Multi-Institutional Study

BACKGROUND

We sought to define the accuracy of preoperative imaging to detect lymph node metastasis (LNM) among patients with pancreatic neuroendocrine tumors (pNETs), as well as characterize the impact of preoperative imaging nodal status on survival.

METHODS

Patients who underwent curative-intent resection for pNETs between 2000 and 2020 were identified from eight centers. Sensitivity and specificity of computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET)-CT, and OctreoScan for LNM were evaluated. The impact of preoperative lymph node status on lymphadenectomy (LND), as well as overall and recurrence-free survival was defined.

RESULTS

Among 852 patients, 235 (27.6%) individuals had LNM on final histologic examination (hN1). The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were 12.4%, 98.1%, 71.8%, and 74.4% for CT, 6.3%, 100%, 100%, and 80.1% for MRI, 9.5%, 100%, 100%, and 58.7% for PET, 11.3%, 97.5%, 66.7%, and 70.8% for OctreoScan, respectively. Among patients with any combination of these imaging modalities, overall sensitivity, specificity, PPV, and NPV was 14.9%, 97.9%, 72.9%, and 75.1%, respectively. Preoperative N1 on imaging (iN1) was associated with a higher number of LND (iN1 13 vs. iN0 9, p = 0.003) and a higher frequency of final hN1 versus preoperative iN0 (iN1 72.9% vs. iN0 24.9%, p < 0.001). Preoperative iN1 was associated with a higher risk of recurrence versus preoperative iN0 (median recurrence-free survival, iN1→hN1 47.5 vs. iN0→hN1 92.7 months, p = 0.05).

CONCLUSIONS

Only 4% of patients with LNM on final pathologic examine had preoperative imaging that was suspicious for LNM. Traditional imaging modalities had low sensitivity to determine nodal status among patients with pNETs.

When Should Lymphadenectomy Be Performed in Non-Metastatic Pancreatic Neuroendocrine Tumors? A Population-Based Analysis of the German Clinical Cancer Registry Group

BACKGROUND

Patient selection for lymphadenectomy remains a controversial aspect in the treatment of pancreatic neuroendocrine tumors (pNETs), given the growing importance of parenchyma-sparing resections and minimally invasive procedures.

METHODS

This population-based analysis was derived from the German Cancer Registry Group during the period from 2000 to 2021. Patients with upfront resected non-functional non-metastatic pNETs were included.

RESULTS

Out of 5520 patients with pNET, 1006 patients met the inclusion criteria. Fifty-three percent of the patients were male. The median age was 64 ± 17 years. G1, G2, and G3 pNETs were found in 57%, 37%, and 7% of the patients, respectively. Lymph node metastasis (LNM) was present in 253 (24%) of all patients. LNM was an independent prognostic factor (HR 1.79, CI 95% 1.21-2.64, p = 0.001) for disease-free survival (DFS). The 3-, 5-, and 10-year disease-free survival in nodal negative tumors compared to nodal positive was 82% vs. 53%, 75% vs. 38%, and 48% vs. 16%. LNM was present in 5% of T1 tumors, 25% of T2 tumors, and 49% of T3-T4 tumors. In T1 tumors, G1 was the most predominant tumor grade (80%). However, in T2 tumors, G2 and G3 represented 44% and 5% of all tumors. LNM was associated with tumors located in the pancreatic head (p < 0.001), positive resection margin (p < 0.001), tumors larger than 2 cm (p < 0.001), and higher tumor grade (p < 0.001). The multivariable analysis showed that tumor size, tumor grade, and location were independent prognostic factors associated with LNM that could potentially be used to predict LNM preoperatively.

CONCLUSION

LNM is an independent negative prognostic factor for DFS in pNETs. Due to the low incidence of LNM in T1 tumors (5%), parenchyma-sparing surgery seems oncologically adequate in small G1 pNETs, while regional lymphadenectomy should be recommended in T2 or G2/G3 pNETs.

Prognostic predictors for recurrence following curative resection in grade I/II pancreatic neuroendocrine tumours

INTRODUCTION

Pancreatic neuroendocrine tumours (pNETs) have an excellent long-term survival after resection, but are associated with a high recurrence rate. Identification of prognostic factors affecting recurrences would enable identifying subgroup of patients at higher risk of recurrences, who may benefit from more aggressive treatment.

METHODS

A retrospective analysis of prospectively maintained database of patients undergoing pancreatectomy with curative intent for grade I and II pNETs between July 2007 and June 2021 was performed. Perioperative and long-term outcomes were analysed.

RESULTS

A total of 68 resected patients of pNETs were included in this analysis. Fifty-two patients (76.47%) underwent pancreaticoduodenectomy, 10 (14.7%) patients had distal pancreatectomy, and 2 (2.9%) patients underwent median pancreatectomy, while enucleation was performed in 4 patients (5.8%). The overall major morbidity (Clavien-Dindo III/IV) and mortality rates were 33.82% and 2.94%, respectively. At a median follow-up period of 48 months, 22 (32.35%) patients had disease recurrence. The 5-year overall survival and 5-year recurrence-free survival (RFS) rates were 90.2% and 60.8%, respectively. While OS was unaffected by different prognostic factors, multivariate analysis showed that lymph node involvement, Ki-67 index ≥5%, and presence of perineural invasion (PNI) were independently associated with recurrence.

CONCLUSIONS

While surgical resection gives excellent overall survival in grade I/II pNETs, lymph node positivity, higher Ki-67 index, and PNI are associated with a high risk for recurrence. Patients with these characteristics should be stratified as high risk and evaluated for more intensive follow-up and aggressive treatment strategies in future prospective studies.

Approaching Small Neuroendocrine Tumors with Radiofrequency Ablation

In recent years, small pancreatic neuroendocrine tumors (pNETs) have shown a dramatic increase in terms of incidence and prevalence, and endoscopic ultrasound (EUS) radiofrequency ablation (RFA) is one potential method to treat the disease in selected patients. As well as the heterogeneity of pNET histology, the studies reported in the literature on EUS-RFA procedures for pNETs are heterogeneous in terms of ablation settings (particularly ablation powers), radiological controls, and radiological indications. The aim of this review is to report the current reported experience in EUS-RFA of small pNETs to help formulate the procedure indications and ablation settings. Another aim is to evaluate the timing and the modality of the radiological surveillance after the ablation. Moreover, new studies on large-scale series are needed in terms of the safety and long-term oncological efficacy of RFA on these small lesions.

Pancreatic Neuroendocrine Neoplasms Larger than 4 cm: A Retrospective Observational Study of Surgery, Histology, and Outcome

BACKGROUND

Pancreatic neuroendocrine neoplasms (pNENs) are often detected as large primary lesions, even with distant metastases, and their prognosis may be difficult to predict.

METHODS

In this retrospective study, we retrieved data of patients treated for a large pNEN in our Surgical Unit (1979-2017) to evaluate the possible prognostic role of clinic-pathological features and surgery. Cox-proportional hazard regression models were used to find possible associations among some variables (clinical features, surgery, and histology) and survival at univariate and multivariate analyses.

RESULTS

Among 333 pNENs, we identified 64 patients (19%) with a lesion > 4 cm. Patients' median age was 61 years, median tumor size was 6.0 cm, and 35 (55%) patients had distant metastases at diagnosis. There were 50 (78%) nonfunctioning pNENs, and 31 tumors localized in the body/tail region of the pancreas. Overall, 36 patients underwent a standard pancreatic resection (with 13 associated liver resection/ablation). Regarding histology, 67% of pNENs were N1, and 34% were grade 2. After a median follow-up of 48 months (up to 33 years), 42 patients died of disease. Median survival after surgery was 79 months, and six patients experienced recurrence (median DFS 94 months). At multivariate analysis, distant metastases were associated with a worse outcome, while having undergone radical tumor resection was a protective factor.

CONCLUSIONS

In our experience, about 20% of pNENs have a size > 4 cm, 78% are nonfunctioning, and 55% show distant metastases at diagnosis. Nevertheless, a long-term survival of more than five years may be achieved after surgery.

Reappraisal of Malignant Risk Assessment for Small (≤20 mm) Non-functioning Pancreatic Neuroendocrine Tumors

BACKGROUND

Optimal management of non-functioning pancreatic neuroendocrine tumors (PanNETs) ≤20 mm is controversial. The biological heterogeneity of these tumors poses challenges when deciding between resection and observation.

METHODS

In this multicenter, retrospective cohort study, we analyzed all patients (n = 78) who underwent resection of non-functioning PanNETs ≤20 mm at three tertiary medical centers from 2004 to 2020 to assess the utility of preoperatively available radiological features and serological biomarkers of non-functioning PanNETs in choosing an optimal surgical indication. The radiological features included non-hyper-attenuation pattern on enhancement computed tomography (CT; hetero/hypo-attenuation) and main pancreatic duct (MPD) involvement, and serological biomarkers included elevation of serum elastase 1 and plasma chromogranin A (CgA) levels.

RESULTS

Of all small non-functioning PanNETs, 5/78 (6%) had lymph node metastasis, 11/76 (14%) were WHO grade II, and 9/66 (14%) had microvascular invasion; 20/78 (26%) had at least one of these high-risk pathological factors. In the preoperative assessment, hetero/hypo-attenuation and MPD involvement were observed in 25/69 (36%) and 8/76 (11%), respectively. Elevated serum elastase 1 and plasma CgA levels were observed in 1/33 (3%) and 0/11 (0%) patients, respectively. On multivariate logistic regression analysis, hetero/hypo-attenuation (odds ratio [OR] 6.1, 95% confidence interval [CI] 1.7-22.2) and MPD involvement (OR 16.8, 95% CI 1.6-174.3) were significantly associated with the high-risk pathological factors. The combination of the two radiological worrisome features correctly predicted non-functioning PanNETs with high-risk pathological factors, with about 75% sensitivity, 79% specificity, and 78% accuracy.

CONCLUSIONS

This combination of radiological worrisome features can accurately predict non-functioning PanNETs that may require resection.

The Emerging Role of m6A Modification in Endocrine Cancer

With the development of RNA modification research, N6-methyladenosine (m6A) is regarded as one of the most important internal epigenetic modifications of eukaryotic mRNA. It is also regulated by methylase, demethylase, and protein preferentially recognizing the m6A modification. This dynamic and reversible post-transcriptional RNA alteration has steadily become the focus of cancer research. It can increase tumor stem cell self-renewal and cell proliferation. The m6A-modified genes may be the primary focus for cancer breakthroughs. Although some endocrine cancers are rare, they may have a high mortality rate. As a result, it is critical to recognize the significance of endocrine cancers and identify new therapeutic targets that will aid in improving disease treatment and prognosis. We summarized the latest experimental progress in the m6A modification in endocrine cancers and proposed the m6A alteration as a potential diagnostic marker for endocrine malignancies.

Contrast Enhanced EUS for Predicting Solid Pancreatic Neuroendocrine Tumor Grade and Aggressiveness

Pancreatic neuroendocrine tumor (PNET) behavior assessment is a daily challenge for physicians. Modern PNET management varies from a watch-and-wait strategy to surgery depending on tumor aggressiveness. Therefore, the aggressiveness definition plays a pivotal role in the PNET work-up. The aggressiveness of PNETs is mainly based on the dimensions and histological grading, with sometimes a lack of specificity and sensibility. In the last twenty years, EUS has become a cornerstone in the diagnostic phase of PNET management for its high diagnostic yield and the possibility of obtaining a histological specimen. The number of EUS applications in the PNET work-up has been rapidly increasing with new and powerful possibilities. The application of contrast has led to an important step in PNET detection; in recent years, it has been gaining interesting applications in aggressiveness assessment. In this review, we underline the latest experiences and opportunities in the behavior assessment of PNETs using contact-enhanced EUS and contested enhanced harmonic EUS with a particular focus on the future application and possibility that these techniques could provide.

Impact of Surgery on Non-Functional Pancreatic Neuroendocrine Tumors ≤2 cm: Analyses With Propensity Score–Based Inverse Probability of Treatment Weighting

Purpose

The impact of surgery on non-functional pancreatic neuroendocrine tumors (NF-PNETs) ≤2 cm is controversial. This study sought to demonstrate the impact of surgery on the prognosis of NF-PNETs ≤2 cm with different biological behaviors.

Methods

Patients with NF-PNETs ≤2 cm from 2004 to 2015 in the Surveillance, Epidemiology, and End Results database were included in this study. An inverse probability of treatment weighting (IPTW) method was used to reduce the selection bias. Kaplan–Meier survival analysis and Cox proportional hazards regression were used to evaluate the effect of surgery on the prognosis.

Results

In the IPTW-adjusted Cox proportional hazards regression analysis, surgery improved the cancer-specific survival (CSS) in the overall cohort (hazard ratio [HR], 0.187; 95% confidence interval [CI], 0.102–0.343; p < 0.001), patients with poorly differentiated or undifferentiated tumor grades (HR, 0.238; 95% CI, 0.105–0.64; p < 0.001), patients with distant metastasis (HR, 0.102; 95% CI, 0.021–0.496; p = 0.005), and patients with local invasion (HR, 0.059; 95% CI, 0.005–0.683; p = 0.002). Surgery did not improve the CSS in patients with lymph node metastasis only (HR, 0.26; 95% CI, 0.0462–1.461; p = 0.126) or patients with well or moderate differentiation while without distant and lymph node metastasis (HR, 0.387; 95% CI, 0.146–1.028; p = 0.057).

Conclusions

Among patients with NF-PNETs ≤2 cm, different biological behaviors correlate with different prognostic impacts of surgery. As long as distant metastasis does not occur and the grade is well–moderately differentiated, these patients will not benefit from surgery no matter whether lymph node metastasis occurs or not. However, when local invasion appears in this group of patients, surgery should be performed. Moreover, patients with a tumor grade of poorly differentiated or undifferentiated or those with distant metastases may benefit from surgery.

Risk factors for lymph node metastasis in patients with pancreatic neuroendocrine neoplasms

BACKGROUND

Although PNENs generally have a better prognosis than pancreatic cancers, some PNENs display malignant behavior including lymph node (LN) metastasis. Complete tumor resection can be the only potentially curative treatment for patients with resectable PNENs. However, the indications for LN dissection are still controversial. Over the last decade, minimally invasive surgery such as laparoscopic pancreatic surgery (LPS) has been increasingly performed for pancreatic tumors including PNENs.

AIM

To investigate the risk factors for LN metastasis in PNENs and to select appropriate patients for limited surgery by LPS.

METHODS

From April 2001 to December 2019, 92 patients underwent pancreatic resection for PNENs at Kumamoto University Hospital. Finally, 82 patients were enrolled in this study. Using perioperative factors, we examined the predictive factors for LN metastasis in PNENs.

RESULTS

Among the 82 patients, the percentage of LN metastasis according to the pathological findings was 12% (10/82 cases). The median tumor size was 12 mm (range: 5-90 mm). The median tumor size in the LN-positive group (37 mm) was significantly larger than that in the LN-negative group (12 mm) (P = 0.0001). Multivariate analyses revealed that larger tumor size (≥ 20 mm) was an independent risk factor for LN metastasis (odds ratio 16.8, P = 0.0062). In patients with small tumors (≤ 10 mm), LN metastasis was not found.

CONCLUSION

Larger tumor size (≥ 20 mm) is an independent risk factor for LN metastasis in PNENs. In smaller PNENs (≤ 10 mm), we may be able to choose limited surgery without LN dissection.

Value of lymphadenectomy in patients with surgically resected pancreatic neuroendocrine tumors

BACKGROUND

Although some factors that predict the prognosis in pancreatic neuroendocrine tumor (pNET) have been confirmed, the predictive value of lymph node metastasis (LNM) in the prognosis of pNETs remains conflicting and it is not clear whether regional lymphadenectomy should be performed in all grades of tumors.

METHODS

We included pNET patients undergoing surgery in Shanghai pancreatic cancer institute (SHPCI). The risk factors for survival were investigated by the Kaplan-Meier method and Cox regression model. We evaluated the predictors of LNM using Logistic regression.

RESULTS

For 206 patients in the SHPCI series, LNM was an independent prognostic factor for entire cohort suggested by multivariate Cox regression analysis. LNM (P = 0.002) predicted poorer overall survival (OS) in grade 2/3 cohort, but there is no significant association between LNM and OS in grade 1 cohort. Grade (P < 0.001) and size (P = 0.049) predicted LNM in entire cohort. Grade (P = 0.002) predicted LNM while regardless of size in grade 2/3 cohort.

CONCLUSIONS

Based on our own retrospective data obtained from a single center series, LNM seems to be associated with poorer outcome for patients with grade 2/3 and/or grade 1 > 4 cm tumors. On the other way, LNM was seems to be not associated with prognosis in patients with grade 1 tumors less than 4 cm. Moreover, tumor grade and tumor size seem to act as independent predictors of LNM. Thus, regional lymphadenectomy should be performed in grade 2/3 patients but was not mandatory in grade 1 tumors < 4 cm. It is reasonable to perform functional sparing surgery for grade 1 patients or propose a clinical-radiological monitoring.

Prognostic factors for relapse in resected gastroenteropancreatic neuroendocrine neoplasms: A systematic review and meta-analysis

BACKGROUND

Gastroenteropancreatic neoplasms (GEP-NENs)can potentially be cured through surgical resection, but only 42-57% achieve 5-year disease-free survival.There is a lack of consensus regarding the factorsassociated withrelapse followingresection ofGEP-NENs.

METHODS

Asystematic review identified studies reporting factors associated with relapse in patients with GEP-NENs following resection of a primary tumour. Meta-analysis was performed to identify the factors prognostic for relapse-free survival (RFS)oroverall survival (OS).

RESULTS

63 studies comprising 13,715 patients were included; 56 studies reported on pancreatic NENs (12,418 patients), 24 reported on patients with grade 1-2 tumours (4,735 patients). Median follow-up was 44.2 months, median RFS was 32 months. Pooling of multivariable analyses of GEP-NENs (all sites and grades) found the following factors predicted worse RFS (all p values < 0.05): vascular resection performed, metastatic disease resected, grade 2 disease, grade 3 disease, tumour size > 20 mm, R1 resection, microvascular invasion, perineural invasion, Ki-67 > 5% and any lymph node positivity. In a subgroup of studies comprising exclusively of grade 1-2 GEP-NENs, R1 resection, perineural invasion, grade 2 disease, any lymph node positivity and tumour size > 20 mm predicted worse RFS (all p values < 0.05). Few OSdata were available for pooling; in univariableanalysis(entire cohort), grade 2 predicted worse OS (p = 0.007), whileR1 resectiondid not (p = 0.14).

CONCLUSIONS

The factors prognostic for worse RFS following resection of a GEP-NEN identified in this meta-analysis could be included in post-curative treatment surveillance clinical guidelines and inform the stratification and inclusion criteria of future adjuvant trials.

A novel risk factor panel predicts early recurrence in resected pancreatic neuroendocrine tumors

BACKGROUND

Pancreatic neuroendocrine tumors (PanNETs) are indolent pancreatic tumors derived from neuroendocrine cells in pancreatic islets. To date, reliable predictors for identifying patients at high risk for recurrence after curative cancer resection are lacking. We aimed to determine independent predictors for high-risk PanNETs and patient outcomes after surgery.

METHODS

We analyzed relevant clinicopathological parameters in 319 consecutive patients of derivation cohort 1 and 106 patients of validation cohort 2 who underwent pancreatectomy and were diagnosed with PanNETs. Association of tumor characteristics with recurrence-free survival (RFS) and overall survival (OS) was evaluated using Cox regression.

RESULTS

PanNET grade 3 (G3), pancreatic duct dilatation, and perineural invasion were independent prognostic factors for RFS and were significantly associated with early recurrence (within 1.5 years) of PanNETs after curative resection (P = 0.019, P < 0.001, and P < 0.001, respectively). Using these factors, we established a novel risk factor panel (R-panel), which predicted early recurrence (P < 0.001, HR = 15.02, 95% CI 5.76-39.19). Predictive accuracy of this R-panel was favorable, with a C-index of 0.853, higher than AJCC TNM staging (0.713). We further built an integrated staging system combining R-panel scoring and TNM staging, which improved predictive probability of TNM staging. Finally, we showed that adjuvant therapy with long-acting somatostatin analogs (SSAs) significantly reduced postoperative recurrence (P < 0.001) and prolonged long-term survival (P = 0.021) in patients with the above risk factors.

CONCLUSION

We identified a novel risk factor panel, which includes PanNET G3, pancreatic duct dilatation, and perineural invasion; this panel predicted early recurrence of PanNETs after curative resection. Patients with these risk factors can benefit from adjuvant therapy with SSAs.

Microscopic Invasion of Nerve Is Associated With Aggressive Behaviors in Pancreatic Neuroendocrine Tumors

Objectives

The role of neural invasion has been reported in cancers. Few studies also showed that neural invasion was related to survival rate in patients with pancreatic neuroendocrine tumor (PNET). The aim of this study is to explore the association between neural invasion and aggressive behaviors in PNET.

Methods

After excluding those patients with biopsy and with missing histological data, a total 197 patients with PNET who underwent surgery were retrospectively analyzed. The demographic data and histological data were obtained. Aggressive behavior was defined based on extra-pancreatic extension including vascular invasion, organ invasion and lymph node metastases. Logistic regression analyses were used to identify risk factor for aggressive behavior. Receiver operating characteristic (ROC) curves were performed to show the performance of nomograms in evaluating aggressive behavior of PNET.

Results

The prevalence of neural invasion in the cohort was 10.1% (n = 20). The prevalence of lymph node metastasis, organ invasion, and vascular invasion in PNET patients with neural invasion was higher than those in patients without neural invasion (p < 0.05). Neural invasion was more common in grade 3 (G3) tumors than G1/G2 (p < 0.01). Tumor size, tumor grade, and neural invasion were independent associated factors of aggressive behavior (p < 0.05) after adjusting for possible cofounders in total tumors and G1/G2 tumors. Two nomograms were developed to predict the aggressive behavior. The area under the ROC curve was 0.84 (95% confidence interval (CI): 0.77–0.90) for total population and was 0.84 (95% CI: 0.78–0.89) for patients with G1/G2 PNET respectively.

Conclusions

Neural invasion is associated with aggressive behavior in PNET. Nomograms based on tumor size, grade and neural invasion show acceptable performances in predicting aggressive behavior in PNET.

Role of Lymph Node Resection and Histopathological Evaluation in Accurate Staging of Nonfunctional Pancreatic Neuroendocrine Tumors: How Many Are Enough?

BACKGROUND

Nodal involvement has been identified as one of the strongest prognostic factors in patients with nonfunctional pancreatic neuroendocrine tumors (NF-PanNETs). Sufficient lymphadenectomy and evaluation is vital for accurate staging. The purpose of this study was to identify the optimal number of examined lymph nodes (ELN) required for accurate staging.

METHODS

The SEER database was used to identify patients with resected NF-PanNETs between 2004 and 2014. The distributions of positive lymph nodes (PLN) ratio and total lymph nodes were used to develop a mathematical model. The sensitivity of detecting nodal disease at each cutoff of ELN was estimated and used to identify the optimal cutoff for ELN.

RESULTS

A total of 1098 patients were included in the study of which 391 patients (35.6%) had nodal disease. The median ELN was 12 (interquartile range [IQR]: 7-19.5), and the median PLN was 2 (IQR: 1-4) for patients with nodal disease. With an increase in ELN, the sensitivity of detecting nodal disease increased from 12.0% (ELN: 1) to 92.2% (ELN: 20), plateauing at 20 ELN (< 1% increase in sensitivity with an additional ELN). This sensitivity increase pattern was similar in subgroup analyses with different T stages.

CONCLUSIONS

The sensitivity of detecting nodal disease in patients with NF-PanNETs increases with an increase in the number of ELN. Cutoffs for adequate nodal assessment were defined for all T stages. Utilization of these cutoffs in clinical settings will help with patient prognostication and management.

c-Myc promotes lymphatic metastasis of pancreatic neuroendocrine tumor through VEGFC upregulation

Pancreatic neuroendocrine tumor (pNET) is a pancreatic neoplasm with neuroendocrine differentiation. pNET in early stage can be treated with surgical resection with long‐term survival, whereas the prognosis of pNET with locoregional or distant metastasis is relatively poor. Lymphangiogenesis is essential for tumor metastasis via the lymphatic system and may overhead distant metastasis. c‐Myc overexpression is involved in tumorigenesis. The role of c‐Myc in lymphangiogenesis is unclear. In this study, we evaluated the mechanism and effect of c‐Myc on lymphangiogenesis of pNET via interaction of lymphatic endothelial cells (LECs) and pNET cells. Lymph node metastasis was evaluated in pNET xenograft mice. Potential target agents to inhibit lymph node metastasis were evaluated in an animal model. We found that vascular endothelial growth factor C (VEGFC) expression and secretion was increased in pNET cell lines with c‐Myc overexpression. c‐Myc transcriptionally upregulates VEGFC expression and the secretion of pNET cells by directly binding to the E‐box of the VEGFC promoter and enhances VEGF receptor 3 phosphorylation and the tube formation of LECs. c‐Myc overexpression is associated with lymph node metastasis in pNET xenograft mice. Combinational treatment with an mTOR inhibitor and c‐Myc inhibitor or VEGFC‐neutralizing chimera protein reduced lymph node metastasis in the mice with c‐Myc overexpression. The mTOR inhibitor acts on lymphangiogenesis by reducing VEGFC expression in pNET cells and inhibiting the tube formation of LECs. In conclusion, mTOR and c‐Myc are important for lymphangiogenesis of pNET and are potential therapeutic targets for prevention and treatment of lymph node metastasis in pNET.

Risk Factors of Lymph Node Metastasis in Patients with Pancreatic Neuroendocrine Tumors (PNETs)

BACKGROUND

The prognostic value of lymph node metastasis in patients with PNETs is controversial. Understanding the effect of lymph node metastasis on prognosis in pancreatic neuroendocrine tumors is helpful for surgery and follow-up. The purposes of this study are to identify predictors of lymph node metastasis among patients with PNETs and determine its prognostic associations.

METHODS

A retrospective analysis of the surveillance, epidemiology, and end results (SEER) database was performed. Patients with PNETs that underwent surgery and pathologic nodal staging were identified. Logistic regression and Cox regression were performed to identify independent predictors and prognostic factors, respectively.

RESULTS

Of 1956 patients (age: 56.8 ± 13.4 years, 53.3% males), 748 (38.2%) had lymph node metastasis. On multivariable analysis, tumor located in pancreas head, distant metastasis, and poorly differentiated, undifferentiated, and unknown differentiated histology grades were three independent risk factors of lymph node metastasis. In the entire cohort, lymph node metastasis indicated a worse overall survival (HR: 1.48, 95% CI: 1.17-1.88, p < 0.001) and disease-specific survival (HR: 1.87, 95% CI: 1.41-2.48, p < 0.001) on multivariable analysis. Lymph node metastasis was associated with worse overall (HR: 1.45, 95% CI: 1.08-1.93, p = 0.012) and disease-specific survival (HR: 2.13, 95% CI: 1.48-3.05, p < 0.001) in patients without distant metastasis on multivariate analysis. Lymph node metastasis was also independently associated with worse disease-specific survival among patients in well differentiation (HR: 2.16, 95% CI: 1.35-3.46, p = 0.001) and moderately differentiation (HR: 2.67, 95% CI: 1.28-5.56, p = 0.009) groups on multivariate analysis.

CONCLUSIONS

Tumor located in pancreas head, distant metastasis, and poorly differentiated, undifferentiated, and unknown differentiated histology grades were three independent risk factors for lymph node metastasis. Lymph node metastasis was an independent prognostic factor of worse OS and DSS in patients with tumor located in pancreas head. Lymph node metastasis was an independent prognostic factor of worse OS and DSS in patients without distant metastasis. Lymph node metastasis was an independent prognostic factor of worse DSS in well differentiation and moderately differentiation groups.

Diffusion-Weighted MRI Predicts Lymph Node Metastasis and Tumor Aggressiveness in Resectable Pancreatic Neuroendocrine Tumors

OBJECTIVES

The aim of this study was to identify whether diffusion-weighted magnetic resonance imaging (DW-MRI) can predict the malignant behavior of preoperative well-differentiated pancreatic neuroendocrine tumors (PanNETs).

METHOD

Forty patients with PanNETs who underwent pancreatectomy were enrolled in this study. The apparent diffusion coefficient (ADC) values were measured. Clinicopathological factors were compared in patients with high ADC and low ADC values and in patients with and without lymph node metastasis (LNM).

RESULT

The low ADC group was significantly associated with higher Ki-67 index, higher mitotic count, larger tumor size, higher rate of LNM, and venous invasion. In patients with low ADC values, the incidence of LNMs was 33.3%. In patients with high ADC values, there were no patients with LNM being 0%. A significant negative correlation was found between the mean ADC values and the Ki-67 index and between the mean ADC values and the mitotic count. In multivariate analysis, neural invasion and mean ADC values ≤ 1458 were independent predictors of LNM.

CONCLUSION

ADC values obtained using DW-MRI in the preoperative assessment of patients with PanNETs might be a useful predictor of malignant potential, especially LNM.

Pattern of disease recurrence and treatment after surgery for nonfunctioning well-differentiated pancreatic neuroendocrine tumors

BACKGROUND

The risk of recurrence after curative surgery for pancreatic neuroendocrine tumors is reported to be between 10% and 30%. Among the available locoregional and systemic treatments, there are no specific recommendations regarding the best option for treating recurrent disease. The aims of this study were to evaluate the pattern of recurrence after surgery performed with curative intent for nonfunctioning pancreatic neuroendocrine tumors and to analyze the impact of treatment on disease progression.

METHODS

All patients submitted to curative surgery for sporadic, well-differentiated, nonfunctioning pancreatic neuroendocrine tumors at 2 Italian centers between 2001 and 2018, with evidence of disease recurrence during follow-up, were included (n = 46).

RESULTS

The most frequent type of recurrence was distant metastases (n = 38, 83%), located in the liver in 100% of cases, whereas 8 patients (17%) had an isolated local recurrence. Therapy for first disease recurrence included both locoregional (n = 14) and systemic treatments (n = 32). A second disease recurrence/progression occurred in 28 patients (61%). Patients who underwent systemic treatment after the first disease recurrence had better progression-free survival (1-year progression-free survival 78%) compared with those submitted to a locoregional procedure (1-year progression-free survival 50%; P = .007). Independent predictors of shortened progression-free survival after the first disease recurrence were the type of treatment (locoregional, hazard ratio 4.452, P = .001), the presence of necrosis (hazard ratio 2.732, P = .022) and age (>60 year, hazard ratio 2.494, P = .040).

CONCLUSION

Upfront locoregional treatment of the first recurrence of nonfunctioning pancreatic neuroendocrine tumors after curative surgery should be avoided in favor of systemic therapy.

Systematic Review and Metaanalysis of Lymph Node Metastases of Resected Pancreatic Neuroendocrine Tumors

BACKGROUND

The optimal surgical strategy for pancreatic neuroendocrine tumors (PNETs) is unknown. However, current guidelines recommend a watch-and-wait strategy for small nonfunctional PNETs (NF-PNETs). The aim of this study is to investigate the risk stratification and prognostic significance of lymph node metastasis (LNM) of PNETs to guide decision-making for lymphadenectomy.

PATIENTS AND METHODS

The MEDLINE and Web of Science databases were systematically searched for studies reporting either risk factors of LNM in resected PNETs or survival of patients with LNM. The weighted average incidence of LNM was calculated according to tumor characteristics. Random-effects metaanalyses were performed, and pooled hazard ratios (HR) and their 95% confidence intervals (CI) were calculated to determine the impact of LNM on overall survival (OS). In subgroup analyses, NF-PNETs were assessed.

RESULTS

From a total of 5883 articles, 98 retrospective studies with 13,374 patients undergoing resection for PNET were included. In all PNETs, the weighted median rates of LNM were 11.5% for small (≤ 2 cm) PNETs and 15.8% for G1 PNETs. In NF-PNETs, the rates were 11.2% for small PNETs and 10.3% for G1 PNETs. LNM of all PNETs (HR 3.87, 95% CI 3.00-4.99, P < 0.001) and NF-PNETs (HR 4.98, 95% CI 2.81-8.83, P < 0.001) was associated with worse OS.

CONCLUSIONS

LNM is potentially prevalent even in small and well-differentiated PNETs and is associated with worse prognosis. A watch-and-wait strategy for small NF-PNETs should be reappraised, and oncologic resection with lymphadenectomy can be considered. Prospective and controlled studies are needed in the future.

Analysis of recurrence after resection of well-differentiated non-functioning pancreatic neuroendocrine tumors

Although pancreatic neuroendocrine tumors (PNETs) are generally considered to have a favorable overall prognosis after resection, disease recurrence has been observed. Few studies have specifically addressed recurrence after resection of PNETs, especially for non-functioning PNETs (NF-PNETs). The aim of our study is to analyze the recurrence of resected well-differentiated NF-PNETs.Patients who underwent surgical resection for grade 1 and 2 NF-PNETs without synchronous metastasis were identified for analysis. Patients were treated from January 2009 to December 2017 in our institution. Univariate and multivariate cox regression analysis were conducted to identify prognostic factors.Of the 88 patients, 46 were men (52%) and the mean age was 52 years. With a median follow-up of 49.1 months (range, 8-122 months), there were 12 recurrences (14%). Liver was the most common recurrence site (7/12, 58%). The 1-, 3-, and 5-year recurrence-free survival was 99%, 90%, and 88%, respectively. Univariate analysis identified that age >52 years, positive lymph nodes, tumor grade 2, and Ki67 index ≥5% were statistically significant. Multivariate analysis identified that Ki67 index ≥5% (hazard ratio [HR], 4.69; 95% confidence interval [CI], 1.36-16.75, P = .015), positive lymph nodes (HR, 6.75; 95% CI, 1.73-24.43, P = .006) were independently associated with recurrence. The 5-year disease-free survival rate was 53% (95% CI, 14.20-91.81%) for patients with Ki-67 ≥5% or (and) positive lymph nodes, while 95% (95% CI, 82.26-100%) for the patients without these 2 factors.Ki67 index and lymph node status are independently associated with recurrence after resection of well-differentiated NF-PNETs in this study.

Circulating Neuroendocrine Gene Transcripts (NETest): A Postoperative Strategy for Early Identification of the Efficacy of Radical Surgery for Pancreatic Neuroendocrine Tumors

BACKGROUND

Surgery remains the only treatment for the cure of pancreatic neuroendocrine tumors (PanNETs). Biomarkers to identify the completeness of resection and predict recurrence are lacking.

OBJECTIVE

The aims of this study were to evaluate if the blood measurement of neuroendocrine gene transcripts (NETest) was diagnostic of PanNETs, and whether NETest blood levels could identify complete resection. We compared transcript analysis with the biomarker chromogranin A (CgA).

METHODS

This was a prospective, longitudinal, single-center study including 30 patients with a postoperative histological confirmation of PanNET. Blood for NETest and CgA was collected preoperatively and on postoperative day (POD) 1, POD5, and POD30. Transcripts were measured by real-time quantitative reverse transcription polymerase chain reaction and multianalyte algorithmic analysis (NETest; normal < 20), and CgA was measured by enzyme-linked immunosorbent assay (ELISA; normal < 109 ng/mL). Data are expressed as mean ± standard deviation (SD).

RESULTS

Pancreatic surgical resections (n = 30) were R0, 26; R1, 2; and R2, 2. Preoperatively, NETest score was elevated in all 30 patients (44.7 ± 27), but postoperatively, NETest scores significantly decreased (p = 0.006) to POD30 (24.7 ± 24). The proportion of patients (15/30) with an elevated score significantly decreased by POD30 (p < 0.0001). CgA levels were elevated preoperatively (184 ± 360 ng/mL) in only 9/30 patients, but did not decrease significantly postoperatively at POD30 (260 ± 589 ng/mL, p = 0.398). The number of patients with elevated CgA levels remained unchanged (9/30).

CONCLUSIONS

The NETest is an accurate diagnostic biomarker for PanNETs (100%). A decrease in NETest levels after radical resection suggests this blood test provides early assessment of surgical efficacy. CgA had no clinical utility.

Prognostic Value and Clinical Predictors of Lymph Node Metastases in Pancreatic Neuroendocrine Tumors

OBJECTIVES

To investigate the correlation between lymph node metastasis (LNM) and various clinicopathological features of pancreatic neuroendocrine tumors (pNETs) and its impact on prognosis.

METHODS

We searched the Surveillance Epidemiology and End Results database (2004-2015) for patients with surgically treated pNETs. Factors correlated with LNMs were analyzed by logistic regression and by Cox analysis.

RESULTS

For tumors of 1 to 4 cm, age (P < 0.001, P = 0.014), grade (P < 0.001, P < 0.001), LNMs (P = 0.008, P < 0.001), and size (P = 0.038, P = 0.002) predicted overall survival (OS) and disease-specific survival (DSS). For tumor greater than 4 cm, age (P < 0.001, P = 0.001) and grade (P = 0.011, P = 0.048) were independent prognostic factors of OS and DSS. Lymph node metastasis modestly predicted DSS (P = 0.028) but not OS (P = 0.218).

CONCLUSIONS

In pNETs greater than 4 cm, LNM is not a predictor of OS and modestly predicts DSS, and lymphadenectomy may be unhelpful in these patients. For pNETs 1 to 4 cm, LNM predicts poor OS and DSS, which supports lymphadenectomy in these patients. Pancreas-sparing resection with only limited peripancreatic node sampling needs to be questioned.

The Evolution of Surgical Strategies for Pancreatic Neuroendocrine Tumors (Pan-NENs): Time-trend and Outcome Analysis From 587 Consecutive Resections at a High-volume Institution

OBJECTIVE

The objective of the present analysis is 2-fold: first, to define the evolution of time trends on the surgical approach to pancreatic neuroendocrine neoplasms (Pan-NENs); second, to perform a complete analysis of the predictors of oncologic outcome.

BACKGROUND

Reflecting their rarity and heterogeneity, Pan-NENs represent a clinical dilemma. In particular, there is a scarcity of data regarding their long-term follow-up after surgical resection.

METHODS

From the Institutional Pan-NEN database, 587 resected cases from 1990 to 2015 were extracted. The time span was arbitrarily divided into 3 discrete clusters enabling a balanced comparison between patient groups. Analyses for predictors of recurrence and survival were performed, together with conditional survival analyses.

RESULTS

Among the 587 resected Pan-NENs, 75% were nonfunctioning tumors, and 5% were syndrome-associated tumors. The mean age was 54 years (±14 years), and 51% of the patients were female. The median tumor size was 20 mm (range 4 to 140), 62% were G1, 32% were G2, and 4% were G3 tumors. Time trends analysis revealed that the number of resected Pan-NENs constantly increased, while the size (from 25 to 20 mm) and G1 proportion (from 65% to 49%) decreased during the study period. After a mean follow-up of 75 months, recurrence analysis revealed that nonfunctioning tumors, tumor grade, N1 status, and vascular invasion were all independent predictors of recurrence. Regardless of size, G1 nonfunctioning tumors with no nodal involvement and vascular invasion had a negligible risk of recurrence at 5 years.

CONCLUSIONS

Pan-NENs have been increasingly diagnosed and resected during the last 3 decades, revealing reliable predictors of outcome. Functioning and nodal status, tumor grade, and vascular invasion accurately predict survival and recurrence with resulting implications for patient follow-up.

Lymphovascular Invasion Predicts Lymph Node Involvement in Small Pancreatic Neuroendocrine Tumors

INTRODUCTION

Pancreatic neuroendocrine tumors (p-NETS) are increasing in incidence, and prognostic factors continue to evolve. The benefit of lymphadenectomy for p-NETS ≤2 cm remains unclear. We sought to determine the significance of lymphovascular invasion (LVI) for small p-NETS.

METHODS

The National Cancer Database was queried for patients with p-NETS ≤2 cm and with ≥1 evaluated lymph node (LN), years 2004-2015. Demographic, clinical, and treatment characteristics were analyzed. Multivariate logistic regression was performed to identify predictors of LN positivity.

RESULTS

Among 2,499 patients identified, tumor location was delineated as the head (26%), body (18%), tail (38%), or unspecified (18%); 74% were well-differentiated versus 10% moderate, 2% poor, and 14% unknown. LVI occurred in 11%. A median of 9 LNs were evaluated; overall positivity was 18%. Mean survival was significantly longer in node-negative patients (115 vs. 95 months, log-rank p < 0.0001). LVI was the strongest predictor of node involvement (OR 10.4, p < 0.0001) when controlling for tumor size, grade, and location. Subset analysis of patients with known LVI status, grade, location, and mitoses found that LVI was more likely in the setting of moderate-to-high tumor grade, 1-2 cm size, pancreatic head location, and high mitotic rate. Among patients with ≥2 of these 4 factors, 25% were node-positive.

CONCLUSIONS

Presence of LVI was the strongest predictor of node positivity. LVI on endoscopic biopsy should prompt resection and regional LN dissection to fully stage patients with small p-NETS. Patients with other high-risk factors should also be considered for resection and regional lymphadenectomy.

The North American Neuroendocrine Tumor Society Consensus Paper on the Surgical Management of Pancreatic Neuroendocrine Tumors

This manuscript is the result of the North American Neuroendocrine Tumor Society consensus conference on the surgical management of pancreatic neuroendocrine tumors from July 19 to 20, 2018. The group reviewed a series of questions of specific interest to surgeons taking care of patients with pancreatic neuroendocrine tumors, and for each, the available literature was reviewed. What follows are these reviews for each question followed by recommendations of the panel.

Prognostic and predictive factors on overall survival and surgical outcomes in pancreatic neuroendocrine tumors: recent advances and controversies

Introduction: Recent advances in diagnostic modalities and therapeutic agents have raised the importance of prognostic factors in predicting overall survival, as well as predictive factors for surgical outcomes, in tailoring therapeutic strategies of patients with pancreatic neuroendocrine neoplasms (panNENs).Areas covered: Numerous recent studies of panNEN patients report the prognostic values of a number of clinically related factors (clinical, laboratory, imaging, treatment-related factors), pathological factors (histological, classification, grading) and molecular factors on long-term survival. In addition, an increasing number of studies showed the usefulness of various factors, specifically biomarkers and molecular makers, in predicting recurrence and mortality related to surgical treatment. Recent findings (from the last 3 years) in each of these areas, as well as recent controversies, are reviewed.Expert commentary: The clinical importance of prognostic and predictive factors for panNENs is markedly increased for both overall outcome and post resection, as a result of recent advances in all aspects of the diagnosis, management and treatment of panNENs. Despite the proven prognostic utility of routinely used tumor grading/classification and staging systems, further studies are required to establish these novel prognostic factors to support their routine clinical use.

A New Scoring System to Predict Recurrent Disease in Grade 1 and 2 Nonfunctional Pancreatic Neuroendocrine Tumors

OBJECTIVE

The aim of this study was to predict recurrence in patients with grade 1 or 2 nonfunctioning pancreatic neuroendocrine tumors (NF-pNET) after curative resection.

BACKGROUND

Surgical resection is the preferred treatment for NF-pNET; however, recurrence occurs frequently after curative surgery, worsening prognosis of patients.

METHODS

Retrospectively, patients with NF-pNET of 3 institutions were included. Patients with distant metastases, hereditary syndromes, or grade 3 tumors were excluded. Local or distant tumor recurrence was scored. Independent predictors for survival and recurrence were identified using Cox-regression analysis. The recurrence score was developed to predict recurrence within 5 years after curative resection of grade 1 to 2 NF-pNET.

RESULTS

With a median follow-up of 51 months, 211 patients with grade 1 to 2 NF-pNET were included. Thirty-five patients (17%) developed recurrence. The 5- and 10-year disease-specific/overall survival was 98%/91% and 84%/68%, respectively. Predictors for recurrence were tumor grade 2, lymph node metastasis, and perineural invasion. On the basis of these predictors, the recurrence score was made. Discrimination [c-statistic 0.81, 95% confidence interval (95% CI) 0.75-0.87] and calibration (Hosmer Lemeshow Chi-square 11.25, P = 0.258) indicated that the ability of the recurrence score to identify patients at risk for recurrence is good.

CONCLUSIONS

This new scoring system could predict recurrence after curative resection of grade 1 and 2 NF-pNET. With the use of the recurrence score, less extensive follow-up could be proposed for patients with low recurrence risk. For high-risk patients, clinical trials should be initiated to investigate whether adjuvant therapy might be beneficial. External validation is ongoing due to limited availability of adequate cohorts.

Significance of Lymph Node Metastasis in Resectable Well-differentiated Pancreatic Neuroendocrine Tumor

OBJECTIVES

Understanding the effect of lymph node metastasis (LNM) on prognosis in pancreatic neuroendocrine neoplasm is helpful for surgery and follow-up. In this study, we investigated the significance of LNM in well-differentiated pancreatic neuroendocrine tumors (PanNETs) according to the World Health Organization 2017 classification.

METHODS

We retrospectively collected data for 95 consecutive patients with PanNET who underwent pancreatic resection with curative intent between January 2008 and December 2017 at 6 institutions. The clinicopathological factors were compared in patients with and without LNM, and prognostic factors were analyzed.

RESULTS

Lymph node metastasis was significantly associated with malignant potential of PanNET, such as larger tumor size, higher Ki-67 index, higher tumor grade, and higher incidence of lymphatic, vessel, and neural invasion. Lymph node metastasis was also associated with disease-free but not overall survival. Multivariate analysis identified NET grade 2 (G2) and G3 as independent risk factors for recurrence after curative resection.

CONCLUSIONS

World Health Organization 2017 classification was the most independent prognostic factor in patients with resectable well-differentiated PanNETs. Patients with G2 and higher-grade tumors require lymph node dissection to improve prognosis.

Time-trend and recurrence analysis of pancreatic neuroendocrine tumors

This study aimed to evaluate the evolving trends in clinicopathological features of pancreatic neuroendocrine tumors and to analyze the predictors of recurrence after curative resection. Data collected retrospectively from a single center between January 1990 and December 2017 were analyzed. Patients were categorized chronologically into three groups for evolving time-trend analysis. Overall, 542 patients (300 female, 55.4%) underwent surgical resection for pancreatic neuroendocrine tumors, including 435 (80.3%) with non-functional tumors. Time-trend analysis revealed that the surgically resected pancreatic neuroendocrine tumor number increased consistently; however, the incidental non-functional pancreatic neuroendocrine tumor number also increased over time (P < 0.001). The 5- and 10-year disease-free survival rates were 86.4 and 81.3%, respectively. The overall recurrence rate was 13.7%, and the most common site of recurrence was the liver. The median time to recurrence after primary surgery was 19.0 (range 0.8-236.3) months, and the median survival time after recurrence was 22.6 (range 0.4-126.9) months. On multivariate analysis, grade G3 pancreatic neuroendocrine tumors (hazard ratio 4.51; P < 0.001), lymph node metastasis (hazard ratio 2.46; P = 0.009), lymphovascular invasion (hazard ratio 3.62; P = 0.004), perineural invasion (hazard ratio 2.61; P = 0.004) and resection margin (hazard ratio 4.20; P = 0.003) were independent prognostic factors of disease-free survival. The surgically resected pancreatic neuroendocrine tumor number increased over time mainly because of an increase in incidentally discovered non-functional pancreatic neuroendocrine tumors. Grade G3 pancreatic neuroendocrine tumors, lymph node metastasis, lymphovascular invasion, perineural invasion and a positive resection margin were significant predictors of worse disease-free survival in patients with surgically resected pancreatic neuroendocrine tumors.

Indications for resection and perioperative outcomes of surgery for pancreatic neuroendocrine neoplasms in Germany: an analysis of the prospective DGAV StuDoQ|Pancreas registry

PURPOSE

Pancreatic neuroendocrine neoplasms (pNENs) are rare, and their surgical management is complex. This study evaluated the current practice of pNEN surgery across Germany, including its adherence with guidelines and its perioperative outcomes.

METHODS

Patients who underwent surgery for pNENs (April 2013-June 2017) were retrieved from the prospective StuDoQ|Pancreas registry of the German Society of General and Visceral Surgery and retrospectively analyzed.

RESULTS

A total of 287 patients (53.7% male) with a mean age of 59.2 ± 14.2 years old underwent pancreatic resection for pNENs. Tumors were localized in the pancreatic head (40.4%), body (23%), or tail (36.6%). A total of 239 (83.3%) patients underwent formal resection with lymphadenectomy, 40 (14%) parenchyma-sparing resection, and 8 (2.8%) only exploration. Fifty (17.4%) patients underwent a minimally invasive approach. Among the 245 patients with complete pathological information, 42 (17.1%) had distant metastases, 78 (31.8%) had stage I tumors, 74 (30.2%) stage II, and 51 (20.8%) stage III. A total of 112 (45.7%) patients had G1 tumors, 101 (41.2%) G2, and 24 (9.8%) G3. Nodal involvement on imaging was an independent predictor of lymph node metastasis according to the multivariable analysis (odds ratio: 0.057; 95% confidence interval: 0.016-0.209; p < 0.01). R0 resection was reported in 240 (83.6%) patients. The 30- and 90-day mortality rates were 2.8% and 4.2%, respectively.

CONCLUSION

In Germany the rate of potential curative resection for pNEN is high. However, formal pancreatic resection seems to be overrepresented, while minimally invasive resection is underrepresented.

Splenic artery as a simple landmark indicating difficulty during laparoscopic distal pancreatectomy

INTRODUCTION

The use of laparoscopic distal pancreatectomy (LDP) is increasing worldwide. It is important for surgeons to predict preoperatively the difficulty and risks of a surgery. However, very few reports have evaluated the impact of patient or tumor factors on the difficulty of LDP. We aimed to determine the predictors of technical difficulties when performing LDP.

METHODS

This study included 34 patients who underwent LDP. Patient information was obtained retrospectively and included age, gender, BMI, primary disease, previous abdominal surgery, previous pancreatitis, tumor size, tumor proximity to the splenic arterial origin, type of splenic artery (SpA), operative time, blood loss, postoperative pancreatic fistula, and length of hospital stay. Univariate and multivariate analyses were performed to determine the predictors of a long operative time. SpA anatomy was classified into two types based on the relationship between its origin and the pancreas. Patients whose SpA origin was upward of the pancreatic parenchyma were classified as SpA type 1, whereas patients whose SpA origin was covered by the pancreatic parenchyma were classified as SpA type 2.

RESULTS

Multivariate analysis revealed SpA type 2 to be an independent risk factor for a long operation (odds ratio = 9.925; 95% confidence interval: 1.461-67.412; P = 0.019). SpA type 2 was related to a longer operative time (P < 0.001) and greater intraoperative blood loss (P = 0.001).

CONCLUSION

Classification according to SpA type is simple and useful for predicting technical difficulty when performing LDP.

Early recurrence of well-differentiated (G1) neuroendocrine liver metastasis after curative-intent surgery: Risk factors and outcome

BACKGROUND

The objective of the current study was to identify the risk of early vs late recurrence of well-differentiated (G1) neuroendocrine liver metastasis (NELM) after curative-intent resection.

METHODS

Patients who underwent curative-intent resection for well-differentiated NELM were identified from a multi-institutional database. Clinicopathological details, as well as the long-term overall (OS) and recurrence free survival (RFS) were obtained and compared. The optimal cutoff value to differentiate early and late recurrence was determined to be 1 year based on trend curve analysis.

RESULTS

Among the 548 patients undergoing curative resection for NELM, 162 patients had a well-differentiated NELM. After a median follow-up of 69 months, 59 (36.4%) patients had tumor recurrence; 23 (39.0%) patients recurred within 1 year (early recurrence) after surgery, while 36 (61.0%) recurred after 1 year (late recurrence). Early recurrence was associated with worse outcome vs late recurrence (5-year OS, 72.4% vs 92.0%; P = 0.020) and no recurrence (5-year OS, 72.4% vs 100.0%; P < 0.001). In addition, postrecurrence survival was worse within 36 months after recurrence among patients who recurred early compared with patients who recurred late (survival after recurrence at 36 months: early recurrence, 71.6% vs late recurrence, 91.4%; P = 0.047), although survival was comparable at 60 months (early recurrence, 71.6% vs late recurrence, 70.0%; P = 0.304). On multivariable analysis, nonfunctional neuroendocrine tumors (hazard ratio [HR], 4.4; 95% confidence interval [CI], 1.2-16.7; P = 0.029) and lymph node metastasis (HR, 3.6; 95% CI, 1.1-11.1; P = 0.028) were independent risk factors for early recurrence, whereas lymph node metastasis (HR, 3.0; 95% CI, 1.2-7.8; P = 0.020) and R1 resection (HR, 3.9; 95% CI, 1.4-10.5; P = 0.008) were independently associated with late recurrence.

CONCLUSIONS

Roughly, one-third of patients with well-differentiated NELM experienced a recurrence following curative-intent surgery. Among patients who recurred, two out of five patients recurred within 1 year after surgery. Early recurrence of well-differentiated NELM was associated with the hormone functional status and lymph node metastasis.

Measurement of circulating transcript levels (NETest) to detect disease recurrence and improve follow-up after curative surgical resection of well-differentiated pancreatic neuroendocrine tumors

BACKGROUND

Recurrence of pancreatic neuroendocrine tumors (pNET) after surgery is common. Strategies to detect recurrence have limitations. We investigated the role of clinical criteria and the multigene polymerase chain reaction-based NETest during post-operative follow-up of pNET.

METHODS

We studied 3 groups of resections: R0 with no recurrence (n = 11), R0 with recurrence (n = 12), and R1 with no recurrence (n = 12). NETest levels (>40%) were compared with chromogranin A (CgA) and clinicopathological criteria (CC; grade, lymph node metastases, size). Nonparametric, receiver operating characteristics, logistic regression, and predictive feature importance analyses were performed.

RESULTS

NETest was higher in R0 with recurrence (56 ± 8%) compared with R1 with no recurrence (39 ± 6%) and R0 with no recurrence (28 ± 6%, P < .005). NETest positively correlated with recurrence (area under the curve: 0.82), CgA was not (area under the curve: 0.51 ± 0.09). Multiple regression analysis defined factor impact as highest for NETest (P < .005) versus CC (P < .03) and CgA (P = .23). NETest gave false positive or negative recurrence in 18% using a 40% cutoff. Logistic regression modeling of CC was 83% accurate; it was 91% when the NETest was included. Combining CC and NETest was approximately 2× more effective than individual CC alone (increase in R ² value from 43% to 80%).

CONCLUSIONS

A multigene blood test facilitates effective identification of pNET recurrence, prediction of disease relapse, and outperforms CgA.

Contrast harmonic EUS for the prediction of pancreatic neuroendocrine tumor aggressiveness (with videos)

BACKGROUND AND AIMS

Contrast harmonic EUS (CH-EUS) has the ability to depict tumor microvasculature. Decreased microvascular density has been identified as a factor associated with tumor aggressiveness. We aimed to study the accuracy of CH-EUS for the prediction of pancreatic neuroendocrine tumor (PNET) aggressiveness.

METHODS

Between June 2009 and March 2015, all consecutive patients with histology-proven PNETs and CH-EUS examination were included. Nine endosonographers blindly analyzed all videos. CH-EUS tumor aggressiveness was defined as a heterogeneous enhancement at the early arterial phase. The final diagnosis of tumor aggressiveness was defined as follows: G3 tumors, morphologic and/or histologic findings of metastatic disease in G1/G2 tumors. Diagnostic values were calculated. Intratumoral microvascular density and fibrosis were assessed on pathologic specimens.

RESULTS

Eighty-one tumors were included, of which 26 were aggressive (32.1%). In CH-EUS 35 tumors (43.2%) had a heterogeneous enhancement. The overall accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of CH-EUS for the diagnosis of tumor aggressiveness were 86%, 96%, 82%, 71%, and 98%, respectively. The interobserver agreement among the 9 endosonographers was good (k = .66). The intraobserver agreement was excellent for the junior (κ = .83) and senior (κ = .82) endosonographers. Heterogeneous tumors at CH-EUS corresponded to fewer vascular and more fibrotic tumors (P < .01).

CONCLUSIONS

CH-EUS is accurate in the prediction of PNET aggressiveness and could be a decision-making element in their management.

A meta-analysis of Prognostic factor of Pancreatic neuroendocrine neoplasms

Pancreatic neuroendocrine neoplasms (pNENs) are a group of clinically rare and heterogeneous diseases of the pancreas. However, the prognostic factors for this disease in patients still remain controversial. The purpose of our study is to evaluate the predictive roles of those prognostic factors for pNENs. All related articles published until Sep 17, 2017 were identified via PubMed, EMBASE, Web of Science, Ovid and the Cochrane Library. Studies that examined the prognostic factors of pNENs were enrolled. 17 articles (2822 patients) were finally included in this study. The pooled data suggested that patients with positive surgical resection margin and lymph node, advanced G stage and TMN stage, organ metastasis, vascular invasion and the necrosis of specimens had a decreased overall survival for pNENs. Similarly, patients with functional tumors might have a poor prognosis. However, age, gender, surgical type and size of tumor could not be regarded as prognostic factors for pNENs. Our analytic data demonstrated that surgical resection margin, G stage, TMN stage, lymph node, metastasis, vascular invasion and the necrosis could be prognostic factors for pNENs. Our study may assist doctors to screen patients with different prognosis more efficiently during follow-up and select appropriate treatment measures.

Preoperative neutrophil-to-lymphocyte ratio and tumor-related factors to predict lymph node metastasis in nonfunctioning pancreatic neuroendocrine tumors

The lymph node (LN) status is very important for the survival in pancreatic neuroendocrine tumors (PNETs). Therefore, the investigation of factors related to LN metastases has a great clinical significance. The aim of this study was to evaluate the predictive value of the preoperative neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR) and possible clinical parameters on the LN metastases in nonfunctional PNETs (NF-PNETs). A retrospective review of 101 NF-PNET patients following curative resection and lymphadenectomy was conducted. The associations between clinicopathological factors and LN metastases and prognosis were determined. Twenty-seven (26.7%) patients had LN metastases. LN metastases was independently associated with disease-free survival (P = 0.009). Ideal cutoff values for predicting LN metastases were 1.80 for NLR, 168.25 for PLR and 2.5 cm for tumor size according to the receiver operating characteristic curve. On multivariable analysis, NLR (P = 0.017), symptomatic diagnosis (P = 0.028) and tumor size (P = 0.020) were associated with LN metastases. These results indicate that preoperative NLR ≥ 1.80, tumor size ≥2.5 cm and symptomatic diagnosis are independently associated with LN metastases for patients undergoing resection of NF-PNETs. It is anticipated that these findings are useful for further planning of lymphadenectomy before surgery.

Intrinsic Contact Between T and N Classifications in Resected Well-Moderately Differentiated Locoregional Pancreatic Neuroendocrine Neoplasms

BACKGROUND

The role of N classification is controversial in several prognostication systems proposed for pancreatic neuroendocrine neoplasms (pNENs). The widely accepted modified European Neuroendocrine Tumor Society (mENETS) system suggests this contradiction may be related to T classification.

METHODS

Data were collected retrospectively from 981 patients in the Surveillance, Epidemiology, and End Results (SEER) database (1973-2012; cohort 1) and 140 patients from the Pancreatic Cancer Institute of Fudan University (2006-2016; cohort 2). All patients had resected well- to moderately differentiated locoregional pNENs, whereby the mENETS system was adopted. Factors related to N1 classification and the association between N and T classifications were analyzed, and N classification prognosis based on T classification was assessed.

RESULTS

In cohorts 1 and 2, tumor size (2-4 cm: p < 0.001 and p = 0.037, respectively; > 4 cm: p < 0.001 and p = 0.012, respectively) and tumors extending beyond the pancreas (p < 0.001 and p = 0.016, respectively), which are factors for T classification, affected N1 classification. For tumors limited to the pancreas, the N1 classification was associated with tumor size (p < 0.001 and p = 0.046, respectively) and predicted poor disease-specific survival (DSS), while for tumors extending beyond the pancreas, the N1 classification did not affect patient outcomes. Findings obtained with data from the SEER database were reproducible with our institutional data.

CONCLUSIONS

N classification is associated with T classification, limiting the value of N1 classification for the pNENs tumor-node-metastasis system. A new risk model is necessary to predict patient outcomes and guide clinical practice for the prognosis of pNENs.

Role of microRNAs in endocrine cancer metastasis

The deregulation of transcription and processing of microRNAs (miRNAs), as well as their function, has been involved in the pathogenesis of several human diseases, including cancer. Despite advances in therapeutic approaches, cancer still represents one of the major health problems worldwide. Cancer metastasis is an aggravating factor in tumor progression, related to increased treatment complexity and a worse prognosis. After more than one decade of extensive studies of miRNAs, the fundamental role of these molecules in cancer progression and metastasis is beginning to be elucidated. Recent evidences have demonstrated a significant role of miRNAs on the metastatic cascade, acting either as pro-metastatic or anti-metastatic. They are involved in distinct steps of metastasis including epithelial-to-mesenchymal transition, migration/invasion, anoikis survival, and distant organ colonization. Studies on the roles of miRNAs in cancer have focused mainly on two fronts: the establishment of a miRNA signature for different tumors, which may aid in early diagnosis using these miRNAs as markers, and functional studies of specific miRNAs, determining their targets, function and regulation. Functional miRNA studies on endocrine cancers are still scarce and represent an important area of research, since some tumors, although not frequent, present a high mortality rate. Among the endocrine tumors, thyroid cancer is the most common and best studied. Several miRNAs show lowered expression in endocrine cancers (i.e. miR-200s, miR-126, miR-7, miR-29a, miR-30a, miR-137, miR-206, miR-101, miR-613, miR-539, miR-205, miR-9, miR-195), while others are commonly overexpressed (i.e. miR-21, miR-183, miR-31, miR-let7b, miR-584, miR-146b, miR-221, miR-222, miR-25, miR-595). Additionally, some miRNAs were found in serum exosomes (miR-151, miR-145, miR-31), potentially serving as diagnostic tools. In this review, we summarize studies concerning the discovery and functions of miRNAs and their regulatory roles in endocrine cancer metastasis, which may contribute for the finding of novel therapeutic targets. The review focus on miRNAs with at least some identified targets, with established functions and, if possible, upstream regulation.

The number of positive lymph node is a better predictor of survival than the lymph node metastasis status for pancreatic neuroendocrine neoplasms: A retrospective cohort study

BACKGROUND

The recently released AJCC TNM staging system of pancreatic adenocarcinoma has endorsed the number of positive lymph node(NPLN) as the criterion of N staging. However, the prognostic role of NPLN is still unclear for pancreatic neuroendocrine neoplasms (pNENs).

METHODS

Patients underwent resection and at least one lymph node examined were identified from the Surveillance, Epidemiology, and End Results database. The overall survival (OS) and disease specific survival (DSS) were estimated using Kaplan-Meier analysis and compared by log-rank test. The prognostic factors were determined by cox proportional regression model.

RESULTS

Totally, 1,269 pNENs were included in the present study. The increasing NPLN (NPLN > 3) was corresponding significantly (P < 0.05) shorter OS and DSS in both entire cohort (OS: NPLN ≤ 3 vs. NPLN > 3, 93.624 ± 1.765 months vs. 75.075 ± 4.005 months; DSS: NPLN ≤ 3 vs. NPLN > 3, 104.829 ± 1.455 months vs. 85.443 ± 3.938 months, respectively) and cohort with the number of examined lymph node more than 11 (OS: NPLN ≤ 3 vs. NPLN > 3, 88.759 ± 2.756 months vs. 73.664 ± 4.700 months; DSS: NPLN ≤ 3 vs. NPLN > 3, 99.021 ± 2.212 months vs. 85.139 ± 4.686 months, respectively). Furthermore, the multivariate analysis showed the NPLN > 3 rather than lymph node status was the independent prognostic factors for OS and DSS in these two cohorts.

CONCLUSIONS

The NPLN seems more meaningful than the lymph node metastasis status as prognostic factor for survival. Taking into account the prognostic value of NPLN for pNENs might improve the current TNM staging systems. However, prospective study is needed to demonstrate our findings.

Prediction of lymph node metastasis in pancreatic neuroendocrine tumors by contrast enhancement characteristics

BACKGROUND

Iso- or hypo-attenuating areas in the arterial phase on contrast-enhanced computed tomography (CE-CT) have been reported to be negative prognostic features in pancreatic neuroendocrine tumors (PNETs). Given that the optimal indication for lymph node dissection in patients with PNET remains unclear, we sought to utilize enhancement characteristics on CE-CT as a preoperative predictor of regional lymph node metastasis in PNETs.

METHODS

The medical records of patients with well-differentiated PNETs who underwent pancreatectomy along with lymphadenectomy were retrospectively analyzed. We divided PNETs into two groups based on the extent of attenuation in the late arterial phase on CE-CT imaging. PNETs that showed hyper-attenuation over the entire area compared to the adjacent normal pancreas were categorized as hyper-PNETs. PNETs that contained both hyper and iso- or hypo-attenuation regions as well as those that showed only iso- or hypo-attenuation over the entire area were categorized as hetero/hypo-PNETs.

RESULTS

Forty-one patients with a median age of 64 years were enrolled, including 11 with hyper-PNETs and 30 with hetero/hypo-PNETs. Hetero/hypo-PNETs were significantly larger than hyper-PNETs (P = 0.022), and the former group more frequently comprised G2 tumors, according to the World Health Organization 2010 classification (P < 0.001). On univariate and multivariate analyses, hetero/hypo-PNETs were independently associated with regional lymph node metastasis.

CONCLUSIONS

The presence of iso- or hypo-attenuating regions appears to be associated with regional lymph node metastasis in PNETs. Tumor enhancement characteristics should be assessed in patients with PNET so as not to miss those at high risk of lymph node metastasis.

Regional Metastatic Behavior of Nonfunctional Pancreatic Neuroendocrine Tumors: Impact of Lymph Node Positivity on Survival

OBJECTIVES

Literature addressing the significance of lymph node positivity in the management of nonfunctional pancreatic neuroendocrine tumors (PNETs) is conflicting.

METHODS

The National Cancer Data Base was queried for patients who underwent surgical resection of nonfunctional PNETs between 1998 and 2011. Clinical data and overall survival were analyzed using χ and Cox proportional hazards regression. Multiple imputation was used as a comparative analysis because of the high number of patients missing data on tumor grade.

RESULTS

Two thousand seven hundred thirty-five patients were identified. The overall incidence of lymph node metastasis was 51%. In the subset of patients with grade 1 tumors less than 1 cm, 24% had positive lymph nodes. Overall median survival for patients with negative lymph nodes was 11 years compared with 8 years for lymph node-positive patients (P < 0.001). On multivariate survival analysis, tumor grade, distant metastases, regional lymph node involvement, positive surgical margins, male sex, and older age were predictive of decreased overall survival.

CONCLUSIONS

Lymph node positivity was associated with decreased overall survival. The incidence of lymph node involvement in resected low-grade tumors less than 1 cm is higher than previously reported. Patients selected for resection of PNETs should be offered lymphadenectomy for staging.

Lymph node ratio, but not the total number of examined lymph nodes or lymph node metastasis, is a predictor of overall survival for pancreatic neuroendocrine neoplasms after surgical resection

Aim

To evaluate the prognostic significance of lymph node metastasis, extent of examined lymph nodes (ELNs) and lymph node ratio (LNR) for resected pancreatic neuroendocrine neoplasms (pNENs).

Materials and Methods

Surgically resected pNENs were assimilated from the Surveillance, Epidemiology, and End Results database. Kaplan-Meier and Cox proportional hazard models were used to examine the prognostic effect of clinicopathological characteristics on overall survival; Harrell's concordance index was performed to assess the prognostic accuracy of all independent prognostic factors; and the Spearman's rank correlation was used to assess the correlation between LNR and other clinicopathological characteristics.

Results

Totally, 1,273 pathologically confirmed pNENs were included in our study. The extent of ELNs failed to show any survival benefit in entire cohort (ELNs ≤ 12 vs. ELNs > 12, P = 0.072) or pNENs without lymph node metastasis (ELNs ≤ 28 vs. ELNs > 28, P = 0.108). Lymph node metastasis and LNR > 0.40 were significantly (both P < 0.001) adverse prognostic factors of overall survival. However, only LNR > 0.40 was the independent predictor of survival after adjusted for other clinicopathological characteristics. Besides LNR, the age, gender, primary tumor site, grade and stage also were the independent predictors of overall survival; and this survival model had an acceptable predictive power (Harrell's concordance index, 0.731).

Conclusions

The current study suggested that the LNR, not the total number of ELNs and the lymph node metastasis, is an independent prognostic indicator of overall survival for pNENs after surgical resection.

Clinical outcomes and prognostic factors of resected pancreatic neuroendocrine neoplasms: A single-center experience in China

The aim of the present study was to investigate the clinical, pathological and prognostic characteristics of Chinese patients with resected pancreatic neuroendocrine neoplasms (p-NENs). Data from patients who were surgically treated and pathologically diagnosed with p-NENs at the Department of Pancreatic Oncology of the Fudan University Shanghai Cancer Center (Shanghai, China), between January 2003 and July 2015, were evaluated using univariate and multivariate analyses. A total of 162 patients with p-NENs met the criteria of the present study and were included in the analysis. Patients with poorly differentiated pancreatic neuroendocrine carcinoma (p-NEC) exhibited a significantly increased rate of lymph node metastasis, as compared with patients with grade (G)1/G2 pancreatic neuroendocrine tumors (p-NETs) (62.5 vs. 20.5%, P=0.003). Univariate analysis identified that the following factors led to decreased overall survival (OS): Lymph node metastasis (P=0.001, vs. the absence of lymph node metastasis); distant metastasis (P=0.043, vs. the absence of distant metastasis); resection margin R1/R2 (P=0.030, vs. R0 resection); NEC G3 (P<0.001, vs. NET G1). Following the multivariate analysis, NEC G3 remained a statistically significant risk factor (HR=12.593; 95% CI, 3.476-45.622; P<0.001, vs. NET G1/G2). Furthermore, according to the proliferation marker protein Ki-67 staining index, assigning a grade using the proliferative index (G1, ≤5%; G2, >5-20%; G3, >20%) was more efficient for prognostic stratification compared with the European Neuroendocrine Tumor Society (Berlin, Germany)/World Health Organization (Geneva, Switzerland) 2010 grading classification. The present study indicated that p-NEC was an important predictor of decreased OS in Chinese patients. Furthermore, a Ki-67 staining index of 5% represented a more efficient value for the distinction between G1 and G2.

Significance of lymph node metastasis in pancreatic neuroendocrine tumor

PURPOSE

Pancreatic neuroendocrine tumor (PNET) is relatively rare and has a generally better prognosis than does pancreatic cancer. However, as its prognosis in patients with lymph node metastasis (LNM) is unclear, lymph node dissection for PNET is controversial. Our study aimed to clarify the significance of LNM in PNET.

METHODS

We retrospectively examined 83 PNET patients who underwent pancreatic resections with lymph node dissection at Kumamoto University Hospital, Saiseikai Kumamoto Hospital, and Kumamoto Regional Medical Center from April 2001 to December 2014. Their clinicopathological parameters were analyzed by the absence or presence of LNM, and with regard to the disease-free survival (DFS) and overall survival (OS). A predictive score of LNM was also made using the age, tumor size, primary tumor location, and tumor function.

RESULTS

Although the 5-year OS was 74.8% for LNM⁺ and 94.6% for LNM^- (P = 0.002), LNM was not an independent risk factor for the OS in a multivariate analysis. However, tumors larger than 1.8 cm were found to be an independent prognostic factor, and the cut-off value for the predictive score was 1.69.

CONCLUSIONS

Although LNM was not an independent prognostic factor, lymph node dissection is recommended for patients whose predictive score is larger than 1.69.

The influence of neural invasion on survival and tumor recurrence in pancreatic ductal adenocarcinoma - A systematic review and meta-analysis

OBJECTIVES

To assess the impact of neural invasion/NI on overall survival/OS and tumor recurrence in pancreatic ductal adenocarcinoma/PDAC.

SUMMARY BACKGROUND DATA

NI is a histopathological hallmark of PDAC. Although some studies suggested an important role for NI on OS, disease-free/DFS and progression-free survival/PFS in PDAC, there is still no consensus on the actual role of NI on survival and local recurrence in PDAC.

METHODS

Pubmed, Cochrane library, Ovid and Google Scholar were screened for the terms "pancreatic ductal adenocarcinoma", "pancreatic cancer", "survival", "tumor recurrence" and "perineural invasion". The Preferred-Reporting-Items-for-Systematic-review-and-Meta-Analysis/PRISMA-guidelines were used for systematic review and meta-analysis. Articles meeting predefined criteria were critically analysed on relevance, and meta-analyses were performed by pooling univariate and multivariate hazard ratios/HR.

RESULTS

A total number of 25 studies on the influence of NI on tumor recurrence, and 121 studies analysing the influence of NI on survival were identified by systematic review. The HR of the univariate (HR 1.88; 95%-CI 1.71-2.07; p < 0.00001) and multivariate meta-analysis (HR 1.68; 95%-CI 1.47-1.92; p < 0.00001) showed a major impact of NI on OS. Likewise, NI was associated with decreased DFS (HR 2.53; 95%-CI: 1.67-3.83; p = 0.0001) and PFS (HR 2.41; 95%-CI: 1.73-3.37: p < 0.00001) multivariate meta-analysis.

CONCLUSIONS

Although the power of this study is limited by missing pathological procedures to assess the true incidence of NI, NI appears to be an independent prognostic factor for OS, DFS and PFS in PDAC. Therefore, NI should be increasingly considered in patient stratification and in the development of novel therapeutic algorithms.

Impact and Clinical Predictors of Lymph Node Metastases in Nonfunctional Pancreatic Neuroendocrine Tumors

Background:

The optimal surgical management of nonfunctional pancreatic neuroendocrine tumors (NF-PNETs) is still controversial. Here, we evaluated the impact of lymph node status on postoperative recurrence in patients with NF-PNET and the potential of preoperative variables for predicting lymph node metastasis (LNM).

Methods:

In this mono-institutional retrospective cohort study conducted in 100 consecutive patients who underwent NF-PNET resection between January 2004 and December 2014, we evaluated risk factors for survival using the Kaplan–Meier method and the Cox regression model. Predictors of LNM were evaluated using the logistic regression model, and the power of predictive models was evaluated using receiver operating characteristic curve analysis.

Results:

Five-year disease-free survival of resected NF-PNET was 64.1%. LNM was independently associated with postoperative recurrence (hazard ratio = 3.995, P = 0.003). Multivariate analysis revealed tumor grade as an independent factor associated with LNM (G2 vs. G1: odds ratio [OR] =6.287, P = 0.008; G3 vs. G1: OR = 12.407, P = 0.001). When tumor grade was excluded, radiological tumor diameter >2.5 cm (OR = 5.430, P = 0.013) and presence of symptoms (OR = 3.366, P = 0.039) were significantly associated with LNM. Compared to neoplasms with radiological diameter >2.5 cm (32.1%), tumors ≤2.5 cm had an obviously lower risk of LNM (7.7%), indicating the reliability of this parameter in predicting LNM (area under the curve, 0.693). Incidentally discovered NF-PNETs ≤2.5 cm were associated with a low-risk of LNM and excellent survival.

Conclusions:

LNM is significantly associated with postoperative recurrence. Radiological tumor diameter is a reliable predictor of LNM in NF-PNETs. Our results indicate that lymphadenectomy in small (≤2.5 cm) NF-PNETs is not routinely necessary.