Biliary Tumor Ablation with Photodynamic Therapy and Radiofrequency Ablation

Ablative therapies for hepatic and biliary tumors: endohepatology coming of age

Ablative therapies refer to minimally invasive procedures performed to destroy abnormal tissue that may arise with many conditions, and can be achieved clinically using chemical, thermal, and other techniques. In this review article, we explore the different ablative therapies used in the management of hepatic and biliary malignancies, namely hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA), with a particular focus on radiofrequency ablation (RFA) and photodynamic therapy (PDT) techniques.

Laser ablation in biliary tree: analysis of the intraductal and superficial thermal effects during the treatment

The treatment of choice for the unresectable cholangiocarcinoma is based on biliary decompression procedures. Despite stent placement is the standard of care, it is related to well-known complications. Hence, alternative techniques were proposed. Ideally, they should guarantee an adequate intraductal disobstruction, without injuring the surrounding tissues.This pre-clinical study aims to investigate the thermal effects of the laser ablation (LA) in the biliary tree, in terms of intraductal and surrounding tissue temperature achieved with different laser settings. The common bile ducts (in their upper and lower portions) of two pigs were ablated for 6 minutes with a diode laser at 3 W and 5 W. A custom-made laser applicator was used to obtain a circumferential ablation within the ducts. The intraductal temperature (T_id) was monitored by means of a fiber Bragg grating (FBG) sensor, while an infrared thermal camera monitored the T distribution in the surrounding tissues (T_sup). A maximum T difference of 65 °C and 57 °C was evidenced between the two power settings for the T_id measured in the upper and lower ducts, respectively. The mean difference between T_id and the averaged T_sup values was evaluated. At 5 W, a difference of 37±3 °C and 44±10 °C were obtained for the upper and lower ducts, respectively. At 3 W, a T difference of 2±1 °C was obtained for the upper biliary duct, while a difference of 8±1 °C was documented for the lower duct. Based on the results obtained in this preliminary study, the possibility to equip the laser probe with temperature sensor can improve the control and the safety of the procedure; this solution will guarantee the monitoring of the treatment while preserving the lumen and the surrounding structures.

Radiofrequency and malignant biliary strictures: An update

Malignant biliary strictures are usually linked to different types of tumors, mainly cholangiocarcinoma, pancreatic and hepatocellular carcinomas. Palliative measures are usually adopted in patients with nonresectable or borderline resectable biliary disease. Stent placement is a well-known and established treatment in patients with unresectable malignancy. Intraductal radiofrequency ablation (RFA) represents a procedure that involves the use of a biliary catheter device, via an endoscopic approach. Indications for biliary RFA described in literature are: Palliative treatment of malignant biliary strictures, avoiding stent occlusion, ablating ingrowth of blocked metal stents, prolonging stent patency, ablating residual adenomatous tissue after endoscopic ampullectomy. In this mini-review we addressed focus on technical success defined as deployment of the RF catheter, virtually succeeded in all patients included in the studies. About efficacy, three main outcome measures have been contemplated: Biliary decompression and stent patency, survival. Existing studies suggest a beneficial effect on survival and stent patency with RFA, but current impression is limited because most of studies have been performed using a retrospective design, on diminutive and dissimilar cohorts of patients.

Laser ablation of the biliary tree: in vivo proof of concept as potential treatment of unresectable cholangiocarcinoma

OBJECTIVES

The palliative treatment of cholangiocarcinoma is based on stent placement with well-known procedure-related complications. Consequently, alternative energy-based techniques were put forward with controversial long-term results. This study aims to evaluate the safety and effectiveness of biliary tree laser ablation (LA) in terms of: (i) absence of perforation, (ii) temperature increase, (iii) induced thermal damage in in vivo models.

MATERIALS AND METHODS

The common bile duct and cystic ducts of two pigs were ablated with a diode laser (circumferential irradiation pattern) for 6 and 3 min at 7 W. Laser settings were chosen from previous ex vivo experiments. Local temperature was monitored through a fibre Bragg grating (FBG) sensor embedded into the laser delivery probe. Histopathological analysis of the ablated specimen was performed through in situ endomicroscopy, haematoxylin and eosin (H&E) and nicotinamide adenine dinucleotide (NADH) stains.

RESULTS

Temperature reached a plateau of 53 °C with consequent thermal damage on the application area, regardless of laser settings and application sites. No perforation was detected macroscopically or microscopically. At the H&E stain, wall integrity was always preserved. The NADH stain allowed to evaluate damage extension. It turned out that the ablation spreading width depended on application time and duct diameter. In situ endomicroscopy revealed a clear distinction between ablated and non-ablated areas.

CONCLUSIONS

The temperature distribution obtained through LA proved to induce a safe and effective intraductal coagulative necrosis of biliary ducts. These results represent the basis for further experiments on tumour-bearing models for the treatment of obstructive cholangiocarcinoma.

Radiofrequency ablation for management of malignant biliary obstruction: a single-center experience and review of the literature

BACKGROUND

Radiofrequency ablation (RFA) causes coagulative necrosis of tissue and may be beneficial prior to biliary stenting. We report our experience using RFA for malignant biliary obstruction and review the literature.

METHODS

Retrospective analysis of all patients undergoing RFA for malignant biliary obstruction over the last two years. Success, complications and re-intervention following RFA were assessed. Controls were age, sex and disease matched who had stenting alone.

RESULTS

31 patients were included and 15 patients underwent biliary RFA prior to stenting (median age 78 years, 8 females). 14 patients had pancreatic cancer, 13 cholangiocarcinoma (6 hilar lesions) and 4 malignant disease invading the bile duct. Adverse events included acute pancreatitis (n = 2) and bacteremia in (n = 1). Median duration of intervention free survival was 220 days in the RFA group compared to 106.5 days in controls (hazard ratio 2.4, 95% CI 1.1 - 5.3, p = 0.025). Multivariable Cox proportional hazard analysis showed survival was associated with RFA (hazard ratio 2.55, 95% CI 1.09-5.96, p = 0.026) but not age, site or type of malignancy.

CONCLUSION

Biliary RFA is a technically feasible with a low adverse event rate and is associated with increased survival. Multi-centre randomized controlled trials are required.

Echoendoscopic ablative therapy for solid pancreatic tumors

Initially, endoscopic ultrasound (EUS) was developed to inspect the pancreas and other organs adjacent to the gastrointestinal tract. After introduction of curvilinear-array echoendoscopes, EUS has been used for a variety of interventions in gastroenterology, including fine needle aspiration, pancreatobiliary drainage and tumor ablation. EUS-guided ablation of pancreatic cystic tumors with ethanol and with or without cytotoxic agents has been studied, showing its potential to become an alternative to surgery. However, only few attempts at using ethanol ablation to treat solid pancreatic tumors have been reported. Recently, EUS-guided radiofrequency ablation was introduced and has been cautiously applied for pancreatic cancer. This article focuses on the clinical application of EUS for the ablation of solid pancreatic tumors.