Role and Operative Technique of Portal Venous Tumor Thrombectomy in Patients with Pancreatic Neuroendocrine Tumors

Venous Thromboembolism in Patients with Neuroendocrine Neoplasms: A Systematic Review of Incidence, Types, and Clinical Outcomes

Background: Neuroendocrine neoplasms (NENs) are a heterogeneous group of tumors with unique biological characteristics and complications, including thromboembolism. This systematic review evaluates the incidence, types, and clinical outcomes of venous thromboembolic events (VTEs) in NEN patients. Methods: A systematic search of PubMed, Scopus, and Embase was conducted to identify studies on TEs in NENs. Eligible studies included case reports, case series, and retrospective cohort studies reporting VTEs, including deep vein thrombosis (DVT), pulmonary embolism (PE), and visceral vein thrombosis (VVT). Data were extracted on tumor site, functionality, differentiation grade, and VTE type. Results: In total, 33 studies were included, comprising 26 case reports, 2 case series, and 5 retrospective cohort studies. VTE prevalence ranged from 7.5% to 33% across studies. The most common VTEs were DVT, PE, and portal vein thrombosis (PVT). A meta-analysis revealed a pooled VTE prevalence of 11.1% (95% CI: 9.07-13.53%). Pancreatic NENs exhibited the highest thrombotic burden, particularly in poorly differentiated and advanced-stage tumors. Functioning tumors, including glucagonomas and ACTH-secreting NENs, were strongly associated with VTEs, potentially related to their systemic effects on coagulation and inflammation. Conclusions: Venous thromboembolism is a significant complication in NEN patients, especially in advanced or poorly differentiated tumors. Early detection and targeted management are critical for improving outcomes. Further investigations are required to clarify the mechanisms underlying thromboembolism in NENs and to develop optimized prophylactic and therapeutic strategies tailored to this patient population.

Revascularization techniques for complete portomesenteric venous occlusion in patients undergoing pancreatic resection

INTRODUCTION

Pancreatic pathologies causing portomesenteric occlusion complicate extirpative pancreatic resection due to portomesenteric hypertension and collateral venous drainage.

METHODS

Patients with portomesenteric occlusion undergoing pancreatectomy were identified between 2007 and 2020 at Stanford University Hospital. Demographic and clinical data, technique and perioperative factors, and post-operative outcomes were analyzed.

RESULTS

Of twenty-seven (27) patients undergoing venous revascularization during pancreatectomy, most (15) were for pancreatic neuroendocrine tumor. Occlusions occurred mostly at the portosplenic confluence (15). Median occlusion length was 4.0 cm [3.1-5.8]. Regarding revascularization strategy, mesocaval shunting was used in 11 patients, in-line venous revascularization with internal jugular conduit in three patients, traditional venous resection and reconstruction in 9 patients, and thrombectomy in two patients. Median cohort operative time and estimated blood loss were 522 min [433-638] and 1000 mL [700-2500], respectively. Median length of stay was 10 days [8-14.5] with overall readmission rate of 37%. Significant complications occurred in 44% of patients despite only one (4%) perioperative mortality.

DISCUSSION

Despite the technical complexity for managing portomesenteric occlusions, early revascularization strategies including mesocaval shunting or in-line venous revascularization are feasible and facilitate a safe pancreatic resection for surgically fit patients.

Advances in Management of Nonfunctional Pancreas Neuroendocrine Tumors

This article presents updates in the surgical management of non-functional sporadic pancreas neuroendocrine tumors NET, including considerations for assessment of biologic behavior to support decision-making, indications for surgery, and surgical approaches tailored to the unique nature of neuroendocrine tumors.

The Risk of Venous Thromboembolism in Neuroendocrine Neoplasms

Neuroendocrine neoplasms (NENs) differ from other malignancies in their ability to produce hormones and biogenic amines, as well as offer a better prognosis in well-differentiated tumors. There are no definite data on the occurrence of thromboembolic events in NENs and no recommendations regarding the use of antithrombotic prophylaxis in this group. Accurate assessment of the thromboembolic risk in NENs represents an important issue, in order to reduce morbidity and mortality due to complications of VTE. The aim of this work was to review the occurrence of thromboembolic events in NENs and the use of antithrombotic prophylaxis in this group. A total of 28 studies identified on PubMed were analyzed. NENs, especially of pancreatic primary, exhibit an increased thrombotic risk. Atypical VTE locations are quite common in NENs. Hormonally active NENs are associated with a significantly increased thromboembolic risk. Further studies in NENs are needed to evaluate the parameters of coagulation and fibrinolysis as predictive biomarkers for VTE complications.

[Highlights of pancreatic surgery: extended indications in pancreatic neuroendocrine tumors]

Advanced pancreatic neuroendocrine tumors (paNET) are mostly characterized by infiltration of vascular structures and/or neighboring organs. The indications for resection in these cases should be measured based on the possibility of an R0 resection. Although the data situation for this rare entity is limited, small case series have shown a significant survival advantage in patients who underwent a radical resection in locally advanced stages of paNET. Both vascular reconstruction and multivisceral resection, when performed at experienced centers, should be considered as curative treatment options. The very special biological behavior of the paNET and the often young patient age justify a much more aggressive approach compared to the pancreatic ductal adenocarcinoma.

Role of surgical treatments in high-grade or advanced gastroenteropancreatic neuroendocrine neoplasms

Over the last 40 years, the incidence and prevalence of gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) have continued to increase. Compared to other epithelial neoplasms in the same organ, GEP-NENs exhibit indolent biological behavior, resulting in more chances to undergo surgery. However, the role of surgery in high-grade or advanced GEP-NENs is still controversial. Surgery is associated with survival improvement of well-differentiated high-grade GEP-NENs, whereas poorly differentiated GEP-NENs that may benefit from resection require careful selection based on Ki67 and other tissue biomarkers. Additionally, surgery also plays an important role in locally advanced and metastatic disease. For locally advanced GEP-NENs, isolated major vascular involvement is no longer an absolute contraindication. In the setting of metastatic GEP-NENs, radical intended surgery is recommended for patients with low-grade and resectable metastases. For unresectable metastatic disease, a variety of surgical approaches, including cytoreduction of liver metastasis, liver transplantation, and surgery after neoadjuvant treatment, show survival benefits. Primary tumor resection in GEP-NENs with unresectable metastatic disease is associated with symptom control, prolonged survival, and improved sensitivity toward systemic therapies. Although there is no established neoadjuvant or adjuvant strategy, increasing attention has been given to this emerging research area. Some studies have reported that neoadjuvant therapy effectively reduces tumor burden, improves the effectiveness of subsequent surgery, and decreases surgical complications.

A novel classification of portal venous tumor invasion to predict residual tumor status after surgery in patients with pancreatic neuroendocrine neoplasms

PURPOSE

To elucidate whether portal venous tumor invasion (PVTI) is a prognostic factor for patients with pancreatic neuroendocrine neoplasms (Pan-NENs).

METHODS

From 2002 to 2019, 240 patients with Pan-NEN were included to examine prognostic factors. PVTI based on computed tomography (CT) images are classified into four types: no PVTI (Vp0/1), PVTI not invading the superior mesenteric vein (Vp2), PVTI invading the superior mesenteric vein or portal vein (Vp3), and PVTI invading the portal bifurcation (Vp4).

RESULTS

Simultaneous liver metastases (SLM) determined the overall survival (OS) in 240 patients. The 5-year OS rates with and without SLM were 46% and 92%, respectively (P < 0.001). PVTIs were observed in 56 of the 240 patients (23%). Among such patients, 39, 11, and 6 had Vp2, Vp3, and Vp4, respectively. The 5-year OS rates with and without PVTI were 62% and 82%, respectively (P < 0.001). Severity of PVTI did not decide PFS and OS after R0/1 resection. There was significant difference in the prognoses between Vp0/1 and Vp2-4. In 161 patients without SLM, 21 had PVTI (13%). According to a multivariate analysis, PVTI and Ki-67 index were independent prognostic factors for progression-free survival (PFS) in patients without SLM. The 5-year PFS rates with and without PVTI were 18% and 77%, respectively (P < 0.001). The 5-year OS rates with and without PVTI were 76% and 95%, respectively (P = 0.02). PVTI was associated with tumor functionality, high serum NSE, and high Ki-67 index.

CONCLUSIONS

PVTI may be a predictor for postoperative recurrence.

Somatostatin-receptor avidity of pancreatic neuroendocrine tumor thrombus in porto-caval venous systems on 99mTc-Octreotide and posttherapeutic 177Lu-DOTA-TATE scans

A 62-year-old woman with a history of abdominal pain presented with multiple hepatic lesions and dilatation of portal, splenic and superior mesenteric veins on the magnetic resonance imaging referred for a 99mTc-octreotide scan. Accordingly, similar octreotide-avid lesions were found as well as an uptake in the epigastric region conforming to the anatomy of the portocaval venous system, compatible with a tumor thrombosis. Then, the patient underwent two cycles of therapy with 177Lu-DOTA-TATE, on that the same appearance was observed. The uptake in the tumor thrombus remained somewhat unchanged, but clinically, a significant improvement of the intractable ascites was achieved.

Portal vein tumor thrombosis after pancreaticoduodenectomy: An extremely rare case of recurrence of pancreatic neuroendocrine neoplasm

Highlight Venous tumor thrombus can occur in association with pancreatic neuroendocrine neoplasm. Ishida and colleagues report their experience with a patient in whom a solitary recurrent tumor developed in the portal vein after pancreaticoduodenectomy for pancreatic neuroendocrine neoplasm. They performed portal vein resection and reconstruction using a left external iliac vein graft.

Rectal Neuroendocrine Tumor With Inferior Vena Cava Tumor Thrombosis Diagnosed With 68Ga-DOTANOC PET/CT

A 69-year-old man with a history of back pain, urinary obstruction, and deep vein thrombosis of both lower extremities 4 years earlier was diagnosed with rectal neuroendocrine tumor, grade 2, Ki-67 index 3%. Ga-DOTANOC PET/CT images showed a left pelvic mass extended to the lumen of the inferior vena cava with a high affinity for somatostatin receptor. A tubular focus of radiotracer accumulation after the course of inferior vena cava with filling defect was suggestive of tumor thrombus.

Extensive Tumor Thrombosis of Portal Venous System Demonstrated on 68Ga-DOTATATE and 68Ga-NODAGA-LM3 PET/CT in a Patient With Well-Differentiated Neuroendocrine Tumor

We present a case with a pancreatic neuroendocrine tumor and extensive tumor thrombosis in portal venous system. The tumor was first identified on contrast-enhanced CT and later confirmed using Ga-DOTATATE and Ga-NODAGA-LM3 PET/CT. Both tracers demonstrated similar pattern with higher tumor affinity and tumor-to-background ratio using Ga-NODAGA-LM3.

Imaging and implications of tumor thrombus in abdominal malignancies: reviewing the basics

Extension of tumor tissue within a vein is a recognized prognostic factor in abdominal malignancy because of its influence on tumor staging and selection of therapeutic management. With the advent of newer surgical techniques, and variable treatment strategies, imaging plays a crucial role in categorizing patients according to the tumor resectability and vascular reconstruction techniques during surgery. Understanding the clinical impact of tumor thrombus increases the awareness of the radiologist about the key findings in tumor staging and decision-making of surgical approach. Ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI) can be used individually and in combination to accurately assess the tumor thrombus. In our pictorial review, we will discuss the imaging findings and clinical consequences of tumor thrombosis in abdominal malignancies, including hepatocellular carcinoma, pancreatic neuroendocrine tumor, renal cancer, and adrenal cortical carcinoma.

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.

Macrovascular venous invasion of pancreatic neuroendocrine tumours: impact on surgical outcomes and survival

BACKGROUND

This study evaluates the impact of macrovascular venous invasion (MVI) on surgical and survival outcomes of pancreatic neuroendocrine tumours (PNETs).

METHODS

We retrospectively reviewed data of 125 patients operated for PNETs. Operative, pathological,and survival outcomes were compared between PNETs with and without MVI.

RESULTS

Macrovascular venous invasion was detected in 25 of 125 PNETs (20%) presenting as tumour thrombi (n = 12) or venous wall invasion (n = 13). MVI was associated with larger tumours, a higher rate of lymph node involvement, less differentiated tumours, and a higher rate of perineural invasion. Resection of PNETS with MVI more often necessitated combined hepatic, venous and multivisceral resections, had a higher rate of intraoperative blood transfusion (p = 0.04) but similar morbidity (44% vs. 42%) and mortality (0 vs. 1%) as PNETs without MVI. PNETs with MVI had a lower median overall survival rate (60 vs. 149 months; p = 0.03). Multivariate analysis revealed that PNETs of the pancreatic head, synchronous liver metastases and higher tumour grade were prognostic factors for overall survival.

CONCLUSIONS

MVI is found in more advanced PNETs. Resection of PNETs with MVI is characterized by increased transfusion rate and reduced overall survival.

Sporadic pancreatic neuroendocrine tumor: Surgery of the primary tumor

The management of patients with sporadic pancreatic neuroendocrine tumors (PNET) is multi-disciplinary and often, multimodal. Surgery has a large part in treatment because it is the only potentially curative therapeutic modality if resection can be complete. The update reviews the operative indications and the different surgical techniques available (including parenchymal-sparing surgery) to treat the primary lesion according to patient status, preoperative work-up and whether the tumor is functioning or not. The place of observation for "small" non-functional sporadic PNET is also discussed.

Gastrinomas: Medical or Surgical Treatment

This article reviews the role of surgical and medical management in patients with Zollinger-Ellison syndrome (ZES) due to a gastrin-secreting neuroendocrine tumor (gastrinoma). It concentrates on the status at present but also briefly reviews the changes over time in treatment approaches. Generally, surgical and medical therapy are complementary today; however, in some cases, such as patients with ZES and multiple endocrine neoplasia type 1, the treatment approach remains controversial.

Tumor thrombosis: a peculiar finding associated with pancreatic neuroendocrine neoplasms. A pictorial essay

While abutment, encasement or vessel occlusion are identified in most patients with a pancreatic tumor, tumor thrombosis is an uncommon finding. In particular, there are no description in the literature of tumor thrombosis associated with ductal adenocarcinoma, the most common pancreatic tumor. On the other hand, surgical series reveal that tumor thrombosis is associated with about 5% of pancreatic neuroendocrine neoplasms (PanNENs), and literature data suggest that this finding is frequently underreported on pre-operative imaging examinations. Tumor thrombosis may be clinically relevant, causing splenoportomesenteric hypertension, possibly responsible for life-threatening upper gastrointestinal bleeding. Bland thrombosis caused by direct infiltration of peri-pancreatic vessels frequently determines surgical unresectability, even in neuroendocrine tumors; on the opposite, tumor thrombosis associated with PanNENs do not exclude surgery per se, even though both morbidity and mortality can be increased by such condition. Considering the favorable prognosis of PanNENs and the frequent need to treat tumor thrombosis in order to prevent complications or to relieve symptoms, it is of paramount importance for radiologists the knowledge of the variety of findings associated with tumor thrombosis in PanNENs.

Role of Fluorouracil, Doxorubicin, and Streptozocin Therapy in the Preoperative Treatment of Localized Pancreatic Neuroendocrine Tumors

INTRODUCTION

5-Fluorouracil, doxorubicin, and streptozocin (FAS) leads to a 39 % response rate in advanced pancreatic neuroendocrine tumors (pNETs). We sought to validate our hypothesis that preoperative FAS may facilitate resection of locoregionally advanced pNETs by reducing the anatomic extent of the primary tumor.

PATIENTS

All patients who received FAS between 2000 and 2012 as initial therapy for a localized pNET were reviewed. Tumor size and vascular relationships were compared on pretreatment and posttreatment imaging studies to quantify treatment response.

RESULTS

Twenty-nine patients received a median 4 cycles of FAS (range 2-15). Rates of RECIST progressive disease (PD), stable disease (SD), and partial response (PR) were 3, 90, and 7 %, respectively. An interface was observed between the tumor and a major mesenteric artery and/or vein in 19 (66 %) and 24 (83 %) patients, respectively; after therapy with FAS, 17 (59 %) and 22 (76 %) had persistent interface with artery and/or vein. Fourteen (48 %) patients underwent pancreatectomy, 7 (50 %) required vascular management, and 9 (64 %) operations were R0. The median overall survival of unresected and resected patients was 41 months (95 % CI, 16-66) and 112 months (95 % CI, 104-120) (P = 0.04).

CONCLUSIONS

Although patients receiving FAS for locoregionally advanced pNETs are unlikely to progress during systemic therapy, significant "downstaging" appears uncommon.