Radiofrequency Thermal Ablation of Metastatic Neuroendocrine Tumors in the Liver

Radiofrequency assisted pancreaticoduodenectomy for palliative surgical resection of locally advanced pancreatic adenocarcinoma

Background

Despite careful patient selection and preoperative investigations curative resection rate (R0) in pancreaticoduodenectomy ranges from 15% to 87%. Here we describe a new palliative approach for pancreaticoduodenectomy using a radiofrequency energy device to ablate tumor in situ in patients undergoing R1/R2 resections for locally advanced pancreatic ductal adenocarcinoma where vascular reconstruction was not feasible.

Results

There was neither postoperative mortality nor significant morbidity. Each time the ablation lasted less than 15 minutes. Following radiofrequency ablation it was observed that the tumor remnant attached to the vessel had shrunk significantly. In four patients this allowed easier separation and dissection of the ablated tumor from the adherent vessel leading to R1 resection. In the other two patients, the ablated tumor did not separate from vessel due to true tumor invasion and patients had an R2 resection. The ablated remnant part of the tumor was left in situ.

Conclusion

Whenever pancreaticoduodenectomy with R0 resection cannot be achieved, this new palliative procedure could be considered in order to facilitate resection and enable maximum destruction in remnant tumors.

Method

Six patients with suspected tumor infiltration and where vascular reconstruction was not warranted underwent radiofrequency-assisted pancreaticoduodenectomy for locally advanced pancreatic ductal adenocarcinoma. Radiofrequency was applied across the tumor vertically 5–10 mm from the edge of the mesenteric and portal veins. Following ablation, the duodenum and the head of pancreas were removed after knife excision along the ablated line. The remaining ablated tissue was left in situ attached to the vessel.

GASTRIC NEUROENDOCRINE TUMOR: REVIEW AND UPDATE

INTRODUCTION

The frequency of gastric neuroendocrine tumors is increasing. Reasons are the popularization of endoscopy and its technical refinements. Despite this, they are still poorly understood and have complex management.

AIM

Update the knowledge on gastric neuroendocrine tumor and expose the future perspectives on the diagnosis and treatment of this disease.

METHOD

Literature review using the following databases: Medline/PubMed, Cochrane Library and SciELO. Search terms were: gastric carcinoid, gastric neuroendocrine tumor, treatment. From the selected articles, 38 were included in this review.

RESULTS

Gastric neuroendocrine tumors are classified in four clinical types. Correct identification of the clinical type and histological grade is fundamental, since treatment varies accordingly and defines survival.

CONCLUSION

Gastric neuroendocrine tumors comprise different subtypes with distinct management and prognosis. Correct identification allows for a tailored therapy. Further studies will clarify the diseases biology and improve its treatment.

Outcome after resection and radiofrequency ablation of liver metastases from small intestinal neuroendocrine tumours

BACKGROUND

In patients with small intestinal neuroendocrine tumour (SI-NET), liver resection or radiofrequency ablation (RFA) of liver metastases is performed for palliation of carcinoid syndrome, and in an effort to improve survival. Data are generally reported from case series, and no randomized trials have studied these treatments. The aim was to compare outcome after liver resection and/or RFA with that of non-surgical treatment in patients with liver metastases from SI-NET.

METHODS

The study included patients with liver metastases from SI-NET who underwent liver RFA/resection or were treated non-surgically. A propensity score match was performed to reduce bias between groups, using baseline variables such as the Charlson co-morbidity index, age, symptoms, carcinoid heart disease, extent of metastases and proliferation index.

RESULTS

Some 103 patients who had RFA and/or liver resection were compared with 273 controls. Propensity score matching resulted in two matched groups, each of 72 patients, with no significant differences in baseline variables. The matched resection/RFA and control groups showed no difference in overall survival (both 74 per cent at 5 years; P = 0·869) or disease-specific survival (74 versus 78 per cent respectively at 5 years; P = 1·000). However, urinary 5-hydroxyindoleacetic acid levels were lower (median 77 versus 120 µmol per 24 h; P = 0·005) and the proportion of patients with progressive disease within the liver was smaller (2 of 18 versus 8 of 18; P < 0·001) in the resection/RFA group after 5 years.

CONCLUSION

These data do not support the use of liver resection and/or RFA in an effort to prolong survival in patients with liver metastases from SI-NET.

Feasible temperature of percutaneous microwave ablation of dog liver abutting the bowel

PURPOSE

This study used a dog model to determine the optimal temperature of percutaneous microwave ablation that causes complete necrosis of liver but not the adjacent bowel, supporting the use of this method to specifically and effectively treat liver tumour abutting the bowel.

MATERIALS AND METHODS

Ultrasound-guided percutaneous microwave ablation of liver abutting the bowel was performed on healthy adult dogs. Temperature of the ablation margin was monitored and controlled through inserted thermal monitoring needles. Dogs were divided into three groups and received microwave ablation at 75-95°C, 65-75°C, or 55-65°C. Imaging and histological examination were used to evaluate the damage of the bowel adjacent to the ablated liver.

RESULTS

Within one hour of treatment, the bowel adjacent to the ablated liver was seriously burned in the group receiving 75-95°C microwave ablation. Inflammation and congestion were found in the submucosa of the bowel in the group receiving 65-75°C microwave ablation. Minor inflammation was found in the mucosa of the bowel in the group receiving 55-65°C microwave ablation. Moreover, in the group receiving 55-65°C microwave ablation, ablated liver areas were covered with omenta, and histological examination revealed inflammatory reaction of the omenta 28 days after ablation.

CONCLUSIONS

Microwave ablation at 55-65°C for 6 min is preferred for ablation of liver tissue abutting the bowel in dogs. These findings may provide some valuable reference for percutaneous microwave ablation of human liver tumour adjacent to the bowel.

Multimodal liver-directed management of neuroendocrine hepatic metastases

A preponderance of patients with neuroendocrine tumors (NETs) will experience hepatic metastases during the course of their disease. Many diagnoses of NETs are made only after the neoplasms have spread from their primary gastroenteropancreatic sites to the liver. This paper reviews current evidence-based treatments for neuroendocrine hepatic metastases, encompassing surgery, hepatic artery embolization (HAE) and chemoembolization (HACE), radioembolization, hepatic artery infusion (HAI), thermal ablation (radiofrequency, microwave, and cryoablation), alcohol ablation, and liver transplantation as therapeutic modalities. Consideration of a multidisciplinary approach to liver-directed therapy is strongly encouraged to limit morbidity and mortality in this patient population.

Radiofrequency ablation of neuroendocrine hepatic metastasis

Neuroendocrine cancer commonly metastasizes to the liver and often presents as unresectable disease. Liver resection or debulking most of the tumor provides a survival advantage for patients. Whether used alone or in combination with resection, radiofrequency ablation provides a unique tool to destroy metastases to the liver and spare hepatic parenchyma. Although randomized trials are lacking, retrospective series provide promising data to consider radiofrequency ablation in the management of hepatic neuroendocrine metastases.

Hepatic ablation for neuroendocrine tumor metastases

The indolent nature of neuroendocrine tumors and their proclivity to be hormonally active warrant aggressive treatment for advanced stage disease with hepatic metastases. Cytoreduction has been associated with improved symptom control as well as prolonged survival compared with those treated with medical therapy. The primary modalities of cytoreduction employed are resection, ablation, and embolization. In particular, radiofrequency ablation has been utilized with good results and minimal morbidity for treating patients with advanced neuroendocrine disease.

Stereotactic body radiation therapy for liver metastases

Although resection is the standard of care for liver metastasis, 80-90% of patients are not resectable at diagnosis. Advances in combination chemotherapy, particularly with targeted agents, have increased tumour response and survival in patients with unresectable metastatic colorectal cancer, but these techniques have limitations and may be associated with high recurrence rates. Some autopsy series have shown that as many as 40% of patients with metastatic colorectal cancer have disease confined to the liver; aggressive local therapy may improve overall survival in such patients. Local control of liver metastases can also ease hepatic capsular pain to improve quality of life. Stereotactic body radiation therapy (SBRT) offers an alternative, non-invasive approach to the treatment of liver metastasis through precisely targeted delivery of radiation to the tumours while minimising normal tissue toxicity. Early applications of SBRT to liver metastases have been promising with the reports of 2-year local control rates of 71-86% and other studies reporting 18-month local control rates of 71-93%. While these data establish the safety of SBRT for liver metastases, more rigorous phase II clinical studies are needed to fully evaluate long-term efficacy and toxicity results. In the interim, this review stresses that SBRT of liver must be performed cautiously given the challenges of organ motion and the low toxicity tolerance of the surrounding hepatic parenchyma.

Peptide receptor therapies in neuroendocrine tumors

Neuroendocrine tumors (NETs) are relatively rare tumors, mainly originating from the digestive system, able to produce bioactive amines and hormones. NETs tend to be slow growing and are often diagnosed when metastatic. The localization of a NETs and the assessment of the extent of disease are crucial for management. Commonly used diagnostic techniques include morphological imaging (ultrasound, computerized tomography, magnetic resonance), and functional imaging (somatostatin receptor scintigraphy, positron emission tomography techniques). Treatment is multidisciplinary and should be individualized according to the tumor type, burden, and symptoms. Therapeutic tools include surgery, interventional radiology, and medical treatments such as somatostatin analogues, interferon, chemotherapy, new targeted drugs and peptide receptor radionuclide therapy (PRRT) with radiolabeled somatostatin analogues. NETs usually over-express somatostatin receptors, thus enabling the therapeutic use of somatostatin analogues, one of the basic tools, able to reduce signs and symptoms of hormone hypersecretion, improve quality of life, and slow tumor growth. PRRT with somatostatin analogues 90Y-DOTATOC and 177Lu-DOTATATE has been explored in NETs for more than a decade. Present knowledge and clinical studies indicate that it is possible to deliver high-absorbed doses to tumors expressing sst2 receptors, with partial and complete objective responses in up to 30% of patients. Side effects, involving the kidney and the bone marrow, are mild if adequate renal protection is used. Moreover, a consistent survival benefit is reported. As NETs may also express cholecystokinin 2, bombesin, neuropeptide Y or vasoactive intestinal peptide receptors even simultaneously, the potential availability and biological stability of radio-analogues will improve the multireceptor targeting of NETs.

Percutaneous microwave ablation of liver cancer adjacent to the gastrointestinal tract

PURPOSE

The purpose of the study was to prospectively evaluate safety and effectiveness of percutaneous microwave ablation under temperature monitoring assisted with ethanol injection for liver cancer abutting gastrointestinal tract.

MATERIALS AND METHODS

One hundred seventy-nine hepatic tumors that underwent percutaneous microwave ablation with curative intention were included. Fifty-three lesions located less than 5 mm from gastrointestinal tract were in gastrointestinal group. One hundred twenty-six lesions located more than 5 mm from hepatic surface and first or second branch of hepatic vessels were in control group. The temperature of marginal ablation tissue proximal to gastrointestinal tract was monitored and controlled to fluctuating between 45 degrees C and 58 degrees C for more than 10 min for tumors in the gastrointestinal group. Ethanol (2-27 ml) was injected into marginal tissue in 33 of 53 lesions of the GI group.

RESULTS

Forty-seven of 53 tumors (88.7%) in the gastrointestinal group and 116 of 126 tumors (92.1%) in the control group achieved complete ablation (p > 0.05). There were neither immediate nor periprocedural complications in both groups. Tumor seeding happened in one of the gastrointestinal group and two of the control group. There was no delayed complication of bile ducts injury.

CONCLUSION

Under strict temperature monitoring, microwave ablation assisted with ethanol injection is safe and achieves a high complete ablation rate for hepatic tumors adjacent to gastrointestinal tract.