Resected Pancreatic Neuroendocrine Tumors: Patterns of Failure and Disease-Related Outcomes With or Without Radiotherapy

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.

Outcomes after high-dose radiation in the management of neuroendocrine neoplasms

BACKGROUND

Neuroendocrine neoplasms (NENs) comprise a rare and heterogenous group of cancers, for which the role of radiation therapy continues to evolve. The purpose of this study is to analyze oncologic outcomes after the use of high-dose radiation in management of NENs at a tertiary hospital.

MATERIALS AND METHODS

We performed a retrospective review of patients who received high-dose radiation with intent to cure or provide durable local control (defined as biologically effective dose (BED) ≥40, α/β = 10) for a localized or metastatic NEN from 2006 to 2019. Evaluation of disease status after radiation was performed according to Response Evaluation Criteria in Solid Tumors (RECIST) criteria when possible. Patients were grouped by differentiation (well-differentiated (WD) or poorly-differentiated (PD)) and stage (localized/locally advanced disease (L) or metastatic (M)) in analysis of probabilities of progression after radiation.

RESULTS

45 patients completed a radiation course with BED ≥40 for a NEN (median BED 72). With a median follow-up of 24 months after radiation, the 2-year actuarial rates of local relapse-free survival, new metastasis-free survival, progression-free survival, and overall survival after radiation were 98%, 45%, 41%, and 69%, respectively. 25 patients (56%) developed new metastases after completion of radiation, including 33% (n = 3) of patients with WD-L disease, 44% (n = 8) of WD-M, 77% (n = 10) of PD-L, and 80% (n = 4) of PD-M, with progressively shorter median times to progression (26, 9, 8, and 3 months, respectively; p = 0.093). Of the 25 patients evaluable by RECIST, 68% (n = 17) achieved either a complete or partial best response in the irradiated lesion.

CONCLUSIONS

These data suggest that focal, high-dose radiation has a role in the management of selected patients with NENs. Local failure is rare in patients with both well-differentiated and poorly-differentiated disease, although the predominant pattern of failure remains development of new metastases.

Neoadjuvant Therapy for Neuroendocrine Neoplasms: Recent Progresses and Future Approaches

Neuroendocrine neoplasms (NENs) are a heterogeneous group of tumors, their treatment being challenging and requiring a multidisciplinary approach. Though the only curative treatment is surgery, up to 50% of patients are diagnosed with metastatic disease. In the last years, neoadjuvant chemo(radio)therapy has become part of the standard of care in the treatment of different cancer types. However, evidence of its efficacy and safety in NEN patients has not yet been confirmed in the literature. The aim of the present review is to perform an extensive review of the scientific evidence for neoadjuvant therapy in patients with gastroenteropancreatic and thoracic NENs.

Meta-Analysis of Prognostic Factors for Recurrence of Resected Well-Differentiated Pancreatic Neuroendocrine Tumors

INTRODUCTION

Well-differentiated pancreatic neuroendocrine tumors (WDPNETs) are a group of rare and heterogeneous tumors. However, the prognostic factors for recurrence after curative resection still remain controversial. We aim to illustrate the prognostic factors for recurrence of resected WDPNETs.

METHODS

All relevant articles published through June 2020 were identified via PubMed, Embase, Web of Science, and Cochrane Library. Articles that examined the prognostic factors of WDPNETs were enrolled.

RESULTS

Ten articles were finally included in this study. From 1993 to 2018, 2,863 patients underwent curative resection and 358 patients had recurrence, and the combined recurrence rate was 13%. Furthermore, the pooled data indicated that patients with G2, positive lymph node and surgical resection margin, vascular invasion, and perineural invasion had a decreased disease-free survival for WDPNETs. However, gender, function, and tumor size had no significant relationship with WDPNETs recurrence.

CONCLUSION

These findings demonstrated that G2, positive lymph node and surgical resection margin, vascular invasion, and perineural invasion could be prognostic factors for recurrence of resected WDPNETs, indicating that patients with these high-risk factors need closer postoperative follow-up and may benefit from adjuvant therapy.

Tumour stem cell markers CD133 and CD44 are useful prognostic factors after surgical resection of pancreatic neuroendocrine tumours

The aim of the present study was to investigate the expression profiles and prognostic values of CD133 and CD44 in a cohort of patients with pancreatic neuroendocrine tumours (PNETs). PNET data from patients who underwent radical resection at the Guangdong Provincial People's Hospital were retrospectively analysed. Immunohistochemistry was performed on PNET samples, and CD133 and CD44 expression was examined. Survival analysis was performed using the Kaplan-Meier method and the log-rank test. A total of 71 cases were included in the study. The mean age of the patients was 45.2 years, and the mean tumour size was 3.3 cm. CD44 expression was positively associated with poor tumour differentiation (P=0.007), high Ki-67 index (P=0.001), added mitotic count (P=0.003), high histological grade (P=0.001) and advanced stage (P=0.025). Similarly, CD133 expression was positively associated with high Ki-67 index (P=0.014) and added mitotic count (P=0.012). However, CD133 expression was not associated with tumour differentiation (P=0.118), histological grade (P=0.126) and stage (P=0.203). Survival analysis revealed that both CD44 and CD133 were prognostic factors for overall survival (OS) and/or disease-free survival (DFS), and that increased co-expression of CD44 and CD133 indicated poor OS and DFS rates in patients with PNET. In patients with no expression or low expression of either CD44 or CD133, a DFS rate of 100% was observed, indicating a low recurrence risk. The present findings suggested that high CD44 and CD133 expression was associated with a poor prognosis in patients with PNET. CD44 and CD133 may be used as prognostic indicators of OS and/or DFS in patients with PNETs.

The Landmark Series: Pancreatic Neuroendocrine Tumors

Pancreatic neuroendocrine tumors (PNETs) comprise a heterogeneous group of neoplasms arising from pancreatic islet cells that remain relatively rare but are increasing in incidence worldwide. While significant advances have been made in recent years with regard to systemic therapies for patients with advanced disease, surgical resection remains the standard of care for most patients with localized tumors. Although formal pancreatectomy with regional lymphadenectomy is the standard approach for most PNETs, pancreas-preserving approaches without formal lymphadenectomy are acceptable for smaller tumors at low risk for lymph node metastases. Furthermore, observation of small, asymptomatic, low-grade PNETs is a safe, initial strategy and is generally recommended for tumors < 1 cm in size. In this Landmark Series review, we highlight the critical studies that have defined the surgical management of PNETs.

The North American Neuroendocrine Tumor Society Consensus Guidelines for Surveillance and Medical Management of Pancreatic Neuroendocrine Tumors

This article is the result of the North American Neuroendocrine Tumor Society consensus conference on the medical management of pancreatic neuroendocrine tumors from July 19 to 20, 2018. The guidelines panel consisted of medical oncologists, pathologists, gastroenterologists, endocrinologists, and radiologists. The panel reviewed a series of questions regarding the medical management of patients with pancreatic neuroendocrine tumors as well as questions regarding surveillance after resection. The available literature was reviewed for each of the question and panel members voted on controversial topics, and the recommendations were included in a document circulated to all panel members for a final approval.

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.

External Beam Radiotherapy in the Treatment of Gastroenteropancreatic Neuroendocrine Tumours: A Systematic Review

AIMS

External beam radiotherapy (EBRT) is infrequently used to treat gastroenteropancreatic neuroendocrine tumours (GEPNETS), with little published data to date. We carried out a systematic review to assess the activity of EBRT for GEPNETS.

MATERIALS AND METHODS

Major databases were searched for papers including at least five patients treated with contemporary EBRT techniques. Eligible studies underwent dual independent review. The primary end points were response rate for lesions treated with definitive intent and recurrence-free survival for primary lesions treated with neoadjuvant or adjuvant intent.

RESULTS

Of 11 included studies (all retrospective), seven investigated pancreatic neuroendocrine tumours (PNETs, 100 patients, 14% grade 3) and four studies investigated extra-pancreatic neuroendocrine tumours (84 patients, 14% grade 3). Trials investigating PNETs administered a median of 50.4 Gy via three-dimensional conformal radiotherapy and intensity-modulated radiotherapy. EBRT was given with neoadjuvant or adjuvant intent in 56 patients, with a recurrence rate of 15%. For the 44 patients not undergoing surgery, the radiological response rate was 46%. Grade 3 + toxicity rates were 11% (acute) and 4% (late). Twelve patients with anorectal neuroendocrine carcinoma received 58 Gy to the primary tumour. Seventy-two patients were treated to sites of metastatic disease (34 bone, 27 brain, 11 soft tissue). Local and distant control were poorly reported. Overall survival ranged from 9 to 19 months. No studies in this group reported toxicity outcomes.

CONCLUSIONS

There are limited, retrospective data on the overall activity and safety of EBRT in GEPNETS. EBRT generally seems to be well tolerated in selected PNET patients with encouraging activity. Well-designed prospective studies in clearly defined populations are required to clarify the role of EBRT in neuroendocrine tumours.

Role of radiotherapy for pancreatobiliary neuroendocrine tumors

Purpose

We investigated the role of radiotherapy (RT) for pancreatobiliary neuroendocrine tumors (PB-NETs).

Materials and Methods

We identified 9 patients with PB-NETs who received RT between January 2005 and March 2012. Of these 9 patients, 4 were diagnosed with NETs in the pancreas and 5 were diagnosed with NETs in the gallbladder. All patients received RT to the primary tumor or resection bed with a median total irradiation dose of 50.4 Gy, with or without chemotherapy.

Results

The tumor response rate and tumor control rate in the RT field were 60% and 100 %, respectively. All 4 patients who underwent surgery had no evidence of disease in the RT field. Of the 5 patients who received RT to the primary gross tumor, 1 had complete response, 2 had partial response, and 2 had stable disease in the RT field. The median time to progression was 11 months. Of the 9 patients, four patients had no progression, and 5 patients had progression of disease (locoregional, 2; distant, 2; locoregional/distant, 1). Of the 4 patients without progression, 3 were treated with RT in adjuvant or neoadjuvant setting, and one received RT to primary tumor. One patient experienced radiation-induced duodenitis at 3 months after concurrent chemoradiation without treatment-related mortality.

Conclusion

RT can yield local control for advanced PB-NETs. RT should be considered an essential part of multimodality treatment in management of advanced PB-NETs.

Cystic pancreatic neuroendocrine tumors: a clinicopathologic study

Pancreatic neuroendocrine tumors (PanNETs) are typically solid neoplasms but in rare instances may present as cystic lesions. This unusual presentation can make clinical diagnosis challenging. In addition, the clinical and histopathologic characteristics of cystic PanNETs are poorly defined. We identified 53 cystic PanNETs in our single-institution experience of 491 surgically resected PanNETs. Similar to solid PanNETs, cystic PanNETs developed with an equal sex distribution and over a wide age range (23 to 91 y; mean, 52 y). The unusual cystic appearance made radiologic differentiation from other cystic pancreatic neoplasms difficult with a misdiagnosis in 23 of 53 (43%) cases. An association between cystic PanNETs and multiple endocrine neoplasia type 1 or multifocal disease [5 of 53 (9%) and 7 of 53 (13%), respectively] was not observed as compared with solid PanNETs (P=0.34 and P=0.31, respectively). Grossly, cystic PanNETs were predominantly located in the tail of the pancreas (n=28, 53%) and were similar in size (mean, 3.3 cm) to solid PanNETs (mean, 4.1 cm; P=0.12). All cysts were unilocular (n=53, 100%) and filled with clear to straw-colored fluid. Larger cysts were sometimes noted to be hemorrhagic. Histologically, the cysts were lined by a thin fibrous band that separated the cyst from the neoplastic cells. In comparison with their solid counterparts, cystic PanNETs were less likely to demonstrate tumor necrosis (6%; P=0.04), perineural invasion (8%; P<0.001), vascular invasion (4%; P<0.001), regional lymph node metastasis (13%; P<0.001), and synchronous distant metastasis (4%; P=0.015). The neoplastic cells of the cystic PanNETs were well differentiated (n=53, 100%) with a low mitotic rate and low Ki-67 proliferation index (range, 0.2% to 11%; mean, 1.8%). On the basis of both the American Joint Cancer Committee and European Neuroendocrine Tumor Society staging systems, the majority of cystic PanNETs presented at a lower pathologic stage as compared with solid PanNETs. In summary, cystic PanNETs are a distinctive subgroup of PanNETs with unique clinical, radiographic, and pathologic features.