Radiofrequency ablation of hepatocellular carcinoma: treatment success as defined by histologic examination of the explanted liver

Hepatocellular cancer response to radiofrequency tumor ablation: contrast-enhanced ultrasound

Radiofrequency ablation (RFA) is increasingly being used as percutaneous treatment of choice for patients with early stage hepatocellular carcinoma (HCC). An accurate assessment of the RFA therapeutic response is of crucial importance, considering that a complete tumor ablation significantly increases patient survival, whereas residual unablated tumor calls for additional treatment. Imaging modalities play a pivotal role in accomplishing this task, but ultrasound (US) is not considered a reliable modality for the evaluation of the real extent of necrosis, even when color/power Doppler techniques are used. Recently, newer microbubble-based US contrast agents used in combination with grey-scale US techniques, which are very sensitive to non-linear behavior of microbubbles, have been introduced. These features have opened new prospects in liver ultrasound and may have a great impact on daily practice, including cost-effective assessment of therapeutic response of percutaneous ablative therapies. Technical evolution of CEUS focusing on findings after RFA are illustrated. These latter are detailed, cross-referenced with the literature and discussed on the basis of our personal experience. Timing of CEUS posttreatment assessment among with advantages and limitations of CEUS are also described with a perspective on further technologic refinement.

Radiofrequency ablation of the liver abutting stomach: in vivo comparison of gastric injury before and after intragastric saline administration in a porcine model

PURPOSE

To compare the in vivo gastric injury observed during radiofrequency (RF) ablation of the liver abutting the stomach before and after the intragastric administration of chilled saline.

MATERIALS AND METHODS

Twenty RF ablation zones were created in the livers of 10 pigs with a 1-cm-exposed active tip of an internally cooled electrode under ultrasound guidance for 10 min. Ten RF ablation zones were created before (non-saline group) and after (saline group) the intragastric administration of approximately 1000 mL of chilled saline, and 20 RF ablation zones were made in the posterior part of the left lobe abutting the stomach. The frequency and severity of the thermal injury observed in the stomach of the two groups were compared histologically.

RESULTS

All the resected gastric specimens showed thermal injuries of varying degrees of severity. The largest diameter of the gastric injury was significantly smaller in the saline group (mean 1.5 cm; range 1.3-1.8 cm) than in the non-saline group (mean 2.1cm; range 1.8-2.4 cm) (p=0.000). The saline group showed significantly less thermal injury to the muscular layer of the gastric wall by the histopathology (p=0.033).

CONCLUSIONS

The intragastric administration of chilled saline might be a useful technique for reducing the severity of gastric injury during RF ablation of the liver abutting the stomach.

Doxorubicin-eluting bead-enhanced radiofrequency ablation of hepatocellular carcinoma: a pilot clinical study

BACKGROUND/AIMS

Experimental studies have shown synergy between radiofrequency (RF) ablation and adjuvant chemotherapy in animal tumour models. We aimed to assess safety and efficacy of doxorubicin-eluting bead (DEB)-enhanced RF ablation in the treatment of human hepatocellular carcinoma (HCC).

METHODS

Twenty patients with single HCC ranging 3.3-7.0 cm (mean, 5.0 cm+/-1.4) showing evidence of residual viable tumour after standard RF ablation underwent intraarterial DEB administration (50-125 mg doxorubicin; mean, 60.2 mg+/-21.8). Follow-up period ranged 6-20 months (mean, 12 months+/-5).

RESULTS

No major complication occurred. No deterioration of liver function was observed. The volume of treatment-induced necrosis--as measured on imaging--increased from 48.1 cm3+/-35.7 after RF ablation to 75.5 cm3+/-52.4 after DEB administration, with an increase of 60.9%+/-39.0. The enhanced effect resulted in confirmed complete response (CR) of the target lesion in 12 (60%) of 20 patients. Incomplete response with persistence of <10% of initial tumour volume was observed in 6 (30%) of 20 patients, and local tumour progression in 2 (10%) of 20.

CONCLUSIONS

Intraarterial DEB administration substantially enhances the effect of RF ablation. DEB-enhanced RF ablation is safe and results in a high rate of CR in patients refractory to standard RF treatment.

Hepatocellular carcinoma: Defining the place of surgery in an era of organ shortage

Liver resection (LR) and transplantation offer the only potential chance of cure for patients with hepatocellular carcinoma (HCC). Historically, all patients were treated by hepatic resection. With the advent of liver transplantation (LT) patients with HCC were preferentially placed on the waiting list for LT. However, early experience with LT was associated with a high rate of tumour recurrence and poor long-term survival. The increasing scarcity of donor livers resulted in restrictions being placed on tumour size, and an improvement in patient survival. To date there have been no randomised clinical trials comparing LR to LT. We review the evidence supporting LR and/or LT for HCC and discuss the role of neoadjuvant therapy. The decision of whether to resect or transplant remains debatable and is often determined by centre experience, availability of LT and donor organs.

Is radiofrequency ablation the treatment of choice for patients with small hepatocellular carcinoma?

Liver resection is widely considered the mainstay of curative therapy for small hepatocellular carcinoma (HCC). Radiofrequency ablation (RFA) was initially developed as a treatment for small HCC in patients with considerable cirrhosis and inadequate liver function reserve for liver resection. However, in some centers, RFA is now used for small HCC, as an alternative to liver resection or even as the preferred treatment. This Practice Point commentary discusses the findings and limitations of a retrospective cohort study by Livraghi et al. that analyzed the outcomes of a group of patients with small, single HCC who underwent treatment with RFA. The authors reported a low major complication rate and a local complete response rate similar to that after resection. This commentary highlights the issues to consider when interpreting and generalizing these results, in particular that these findings need to be interpreted in the light of studies that suggest a high rate of local recurrence and incomplete histopathological response after RFA of small HCC.

Risk factors and prognostic factors of local recurrence after radiofrequency ablation of hepatocellular carcinoma

BACKGROUND

Local recurrence rates after radiofrequency ablation (RFA) of hepatocellular carcinoma (HCC) vary from 2% to 36% in the literature. Limited data were available about the prognostic significance of local recurrence.

STUDY DESIGN

Between April 2001 and March 2006, 273 patients with 357 hepatocellular carcinoma nodules underwent RFA, with radiologically complete tumor ablation after a single session of RFA. The risk factors of local recurrence and its impact on overall survival of patients were analyzed.

RESULTS

With a median followup period of 24 months, local recurrence occurred in 35 patients (12.8%). By multivariate analysis, tumor size > 2.5 cm was the only independent risk factor for local recurrence. There was no notable difference in overall survival between patients with and without local recurrence. By multivariate analysis, local recurrence more than 12 months after RFA and complete response after additional treatment of local recurrence were associated with better overall survival in patients with local recurrence.

CONCLUSIONS

This study demonstrated that tumor size > 2.5 cm was the main risk factor for local recurrence after RFA of hepatocellular carcinoma. Our data suggested that additional aggressive treatment of local recurrence aimed at complete tumor response improves overall survival of patients. Late local recurrence was also associated with better prognosis, suggesting different tumor biology between early and late local recurrent tumors after RFA.

Current situation and progress of local ablation therapy for hepatocellular carcinoma

Local ablation therapy with satisfactory therapeutic effects has been an important combined therapy for hepatocellular carcinoma (HCC). There are mainly two ablation methods available including thermal ablation and chemical ablation. Thermal ablation techniques include microwave ablation, radiofrequency ablation, laser ablation, high intensity focus ultrasound (HIFU) and cryoablation, etc. Chemical ablation methods include mainly ethanol ablation and acetic acid ablation. In this article, our objective was to evaluate the current situation and progress of local ablation therapy in terms of its principles, indications, therapeutic effects, complications, contraindications and pros and cons of various ablation therapies for HCC.

Percutaneous radiofrequency ablation of liver dome hepatocellular carcinoma invisible on ultrasonography: a new targeting strategy

Targeting of index tumours is prerequisite to their radiofrequency ablation. However, small hepatocellular carcinomas (HCCs) in the liver dome are often invisible on ultrasonography, thus causing difficulty in their targeting. In cases with multinodular HCCs, adjacent HCC lesions with compact iodized oil retention can be used as anatomic landmarks to guide radiofrequency (RF) ablation of such nodules under fluoroscopy. We present two cases in which nodules that were difficult to target with conventional methods were successfully treated by RF ablation using this targeting strategy.

MR Imaging of hepatocellular carcinoma in the cirrhotic liver: challenges and controversies

The incidence of hepatocellular carcinoma (HCC) is expected to increase in the next 2 decades, largely due to hepatitis C infection and secondary cirrhosis. HCC is being detected at an earlier stage owing to the implementation of screening programs. Biopsy is no longer required prior to treatment, and diagnosis of HCC is heavily dependent on imaging characteristics. The most recent recommendations by the American Association for the Study of Liver Diseases (AASLD) state that a diagnosis of HCC can be made if a mass larger than 2 cm shows typical features of HCC (hypervascularity in the arterial phase and washout in the venous phase) at contrast material-enhanced computed tomography or magnetic resonance (MR) imaging or if a mass measuring 1-2 cm shows these features at both modalities. There is an ever-increasing demand on radiologists to detect smaller tumors, when curative therapies are most effective. However, the major difficulty in imaging cirrhosis is the characterization of hypervascular nodules smaller than 2 cm, which often have nonspecific imaging characteristics. The authors present a review of the MR imaging and pathologic features of regenerative nodules and dysplastic nodules and focus on HCC in the cirrhotic liver, with particular reference to small tumors and lesions that may mimic HCC. The authors also review the sensitivity of MR imaging for the detection of these tumors and discuss the staging of HCC and the treatment options in the context of the guidelines of the AASLD and the imaging criteria required by the United Network for Organ Sharing for transplantation. MR findings following ablation and chemoembolization are also reviewed.

Large (>or=5.0-cm) HCCs: multipolar RF ablation with three internally cooled bipolar electrodes--initial experience in 26 patients

PURPOSE

To prospectively evaluate the safety and effectiveness of percutaneous multipolar radiofrequency (RF) ablation for the treatment of large (>or=5.0 cm in diameter) hepatocellular carcinomas (HCCs).

MATERIALS AND METHODS

Twenty-six patients (four women, 22 men; median age, 72 years) with cirrhosis (Child-Pugh class A disease, 22 patients; Child-Pugh class B disease, four patients) and at least one 5.0-9.0-cm-diameter HCC without invasion of the portal trunk or main portal branches were treated with multipolar RF ablation performed by a single operator. The procedure was performed with three separate bipolar linear internally cooled electrodes with ultrasonographic guidance. Twenty-seven of the 33 tumors treated had a diameter of 5.0 cm or greater (median diameter, 5.7 cm; range, 5.0-8.5 cm); 12 of these 27 tumors were infiltrative, and four invaded segmental portal vein branches. Ten patients had a serum alpha-fetoprotein level higher than 400 microg/L. Results were assessed by using computed tomography. Primary effectiveness, complications, tumor progression, and survival rates were recorded. Probabilities of survival were calculated by using the Kaplan-Meier method.

RESULTS

One to two RF ablation procedures per patient (mean, 1.15 +/- 0.43 [standard deviation]) led to the complete ablation of 22 (81%) of the 27 tumors (18 tumors after one and four tumors after two procedures), including three tumors that showed segmental portal vein invasion. All patients experienced postablation syndrome, and one experienced subcapsular hematoma and a segmental liver infarct, but no major complication occurred. After a mean follow-up of 14 months (range, 3-34 months), local and distant tumor progression and actual survival rates were 14% (three of 22), 24% (five of 21), and 65% (17 of 26), respectively. The probabilities of 1- and 2-year survival, respectively, were 68% (95% confidence interval: 49%, 86%) and 56% (95% confidence interval: 51%, 81%).

CONCLUSION

HCCs larger than 5.0 cm (but smaller than 9.0 cm)--even those that are infiltrative and those that involve a segmental portal vein--can be completely and safely ablated with multipolar RF ablation.

Influence of approach on outcome in radiofrequency ablation of liver tumors

In this article some recent data concerning the approach on radiofrequency ablation (RFA) of liver tumors are reviewed. Specifically, several critical statements between surgical and percutaneous approach are raised and discussed: (1) Open approach may lead to a higher complication rate; (2) Temporary occlusion of hepatic inflow during surgical approach may lead to a higher rate of ablation of the liver tumors; (3) Surgical approach may permit better targeting of the tumor to be ablated. (4) Surgical approach may discover additional liver tumors. Finally, several conclusions and recommendations are also addressed.

Diffusion-weighted MR: therapeutic evaluation after chemoembolization of VX-2 carcinoma implanted in rabbit liver

RATIONALE AND OBJECTIVES

The study goal was to evaluate the ability of diffusion-weighted imaging (DWI) in assessing the viability of rabbit liver VX-2 tumor after transcatheter arterial chemoembolization (TACE).

MATERIALS AND METHODS

VX-2 tumors were grown in the livers of 19 rabbits, and chemoembolization was performed. MR imaging was acquired 1 week after TACE. The rabbits were killed for histologic investigation immediately after MR imaging, and the proportion of viable tumor was calculated based on histopathologic examination. Apparent diffusion coefficient (ADC) values were measured in viable and necrotic tumor portion, and were compared using the paired Student's t test.

RESULTS

Viable tumors were absent (n = 3), less than 5% (n = 6), and 5% or more (n = 10) at pathology examination. On DWI, three tumors with no viable portion were interpreted as having no viable portion, but three of six tumors with a viable portion of less than 5% were considered as having no viable portion. The mean ADC values of necrotic and viable tumor were 1.653 +/- 0.126 mm(2)/sec and 0.883 +/- 0.407 mm(2)/sec (b = 1000 sec/mm(2)), respectively, and the ADC values of necrotic tumors were significantly greater than those in viable tumors (p < .01).

CONCLUSION

Although DWI is a useful tool for assessing tumor viability, viable tumor may not be detected on DWI when it is too small.

Combined percutaneous radiofrequency ablation and ethanol injection for hepatocellular carcinoma in high-risk locations

OBJECTIVE

The purpose of this study was to investigate whether combining percutaneous ethanol injection (PEI) with radiofrequency ablation in the management of hepatocellular carcinoma (HCC) in high-risk locations improves treatment outcomes.

SUBJECTS AND METHODS

We compared the outcome of management of high-risk tumors with PEI and radiofrequency ablation (n = 50) or radiofrequency ablation alone (n = 114) with the outcome of radiofrequency ablation of non-high-risk tumors (n = 44). We also compared the survival rates of patients with and those without high-risk HCC. PEI was performed into the part of the tumor closest to a blood vessel or vital structure before radiofrequency ablation.

RESULTS

The study included 142 patients with 208 HCCs managed with radiofrequency ablation. Despite larger tumor sizes (2.8 +/- 1 cm vs 1.9 +/- 0.7 cm vs 2.5 +/- 0.1 cm for the high-risk radiofrequency plus PEI, non-high-risk radiofrequency, and high-risk radiofrequency groups, respectively; p < 0.001), the primary effectiveness rate of high-risk radiofrequency ablation and PEI (92%) was similar to that of non-high-risk radiofrequency ablation (96%). The primary effectiveness rate of high-risk radiofrequency ablation and PEI was slightly higher (p = 0.1) than that of high-risk radiofrequency ablation (85%). The local tumor progression rates (21% vs 33% vs 24% at 18 months) of the three respective groups were not statistically different (p = 0.91). Patients with and those without high-risk tumors had equal survival rates (p = 0.42) after 12 (87% vs 100%) and 24 (77% vs 80%) months of follow-up. Independent predictors of primary effectiveness were a tumor size of 3 cm or less (p = 0.01) and distinct tumor borders (p = 0.009). Indistinct borders (p = 0.033) and non-treatment-naive status of HCC (p = 0.002) were associated with higher local tumor progression rates. The only predictor of survival was complete ablation of all index tumors (p = 0.001).

CONCLUSION

The combination of radiofrequency ablation and PEI in the management of HCC in high-risk locations has a slightly higher primary effectiveness rate than does radiofrequency ablation alone. A randomized controlled study is warranted.

Incomplete ablation after radiofrequency ablation of hepatocellular carcinoma: analysis of risk factors and prognostic factors

BACKGROUND

Complete ablation rates after a single session of radiofrequency ablation (RFA) of hepatocellular carcinoma (HCC) vary from 48% to 97%. Limited data are available regarding risk factors and prognostic significance of incomplete ablation.

METHODS

Between April 2001 and March 2006, 298 patients underwent RFA of 393 HCC nodules with an intent of complete ablation after a single session. Risk factors for incomplete ablation and its effect on overall survival were analyzed.

RESULTS

Two hundred seventy-three (91.6%) underwent complete tumor ablation, whereas the other 25 (8.4%) underwent incomplete tumor ablation after a single session of RFA. By multivariate analysis, tumor size > 3 cm (P = .049) was found to be the only independent risk factor for incomplete ablation. There was no statistically significant difference in overall survival between patients with complete and incomplete ablation. By univariate analysis, no previous transarterial chemoembolization (TACE), preoperative serum alfa-fetoprotein < or = 100 microg/mL, and complete response after further treatment of incomplete ablation were associated with better overall survival in patients with incomplete ablation.

CONCLUSIONS

This study demonstrated that incomplete ablation after RFA of HCC was associated with tumor size > 3 cm. Our data also suggest that aggressive further treatment of tumors with incomplete ablation aiming at complete tumor response improves overall survival.

Thermal ablation of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the fifth most common cause of cancer, and its incidence is increasing worldwide because of the dissemination of hepatitis B and C virus infection. Patients with cirrhosis are at the highest risk of developing HCC and should be monitored every 6 months to diagnose the tumour at an early, asymptomatic stage. Patients with early-stage HCC should be considered for any of the available curative therapies, including surgical resection, liver transplantation and percutaneous image-guided ablation. Liver transplantation is the only option that provides cure of both the tumour and the underlying chronic liver disease. However, the lack of sufficient liver donation greatly limits its applicability. Resection is the treatment of choice for HCC in non-cirrhotic patients, who account for about 5% of the cases in western countries. However, in patients with cirrhosis, candidates for resection have to be carefully selected to reduce the risk of postoperative liver failure. It has been shown that a normal bilirubin concentration and the absence of clinically significant portal hypertension are the best predictors of excellent outcomes after surgery. However, less than 5% of cirrhotic patients with HCC fit these criteria. Image-guided percutaneous ablation is the best therapeutic choice for non-surgical patients with early-stage HCC. While ethanol injection has been the seminal percutaneous technique, radiofrequency ablation has emerged as the most effective method for local tumour destruction and is currently used as the primary ablative modality at most institutions.

Treatment before liver transplantation for HCC

Liver transplantation (LT) which is currently an established therapy for sma1l, early stage hepatocellular carcinoma (HCC) in patients with cirrhosis requires in most cases long waiting period. Tumor development during the waiting period may be associated with vascular invasion which is a strong factor of postoperative recurrence. Therefore, local treatment of the tumor including trans-arterial chemoembolization (TACE), percutaneous radiofrequency (RF) or partial liver resection can be used before transplantation. In the present paper we reviewed the efficacy of these treatments prior to LT. Although, TACE induced complete tumor necrosis in some patients there is no convincing arguments showing that this treatment reduces the rate of drop out before LT, nor improves the survival after LT. Although, RF can induce complete necrosis in the majority of small tumors (<2.5 cm), there is no data demonstrating that this treatment reduce the rate of drop out before LT, nor improves the survival after LT. It has been showed that both short and long term survival after LT was not compromised by previous partial liver resection of HCC. However, there is no data demonstrating that liver resection before LT, which can be used either as a bridge treatment or as a primary treatment, improves the survival after LT. The current data suggest that there is no role for pre-transplant therapy for HCC within Milano criteria transplanted within six months. On the opposite, if the waiting time is predicted to be prolonged, the risk of tumor progression and either drop-off from the list or interval dissemination with post-transplant tumor recurrence is recognized. In this setting, bridge therapy can reduce that risk but its efficacy has to be determined.

Factors limiting complete tumor ablation by radiofrequency ablation

The purpose of this study was to determine radiological or physical factors to predict the risk of residual mass or local recurrence of primary and secondary hepatic tumors treated by radiofrequency ablation (RFA). Eighty-two patients, with 146 lesions (80 hepatocellular carcinomas, 66 metastases), were treated by RFA. Morphological parameters of the lesions included size, location, number, ultrasound echogenicity, computed tomography density, and magnetic resonance signal intensity were obtained before and after treatment. Parameters of the generator were recorded during radiofrequency application. The recurrence-free group was statistically compared to the recurrence and residual mass groups on all these parameters. Twenty residual masses were detected. Twenty-nine lesions recurred after a mean follow-up of 18 months. Size was a predictive parameter. Patients' sex and age and the echogenicity and density of lesions were significantly different for the recurrence and residual mass groups compared to the recurrence-free group (p < 0.05). The presence of an enhanced ring on the magnetic resonance control was more frequent in the recurrence and residual mass groups. In the group of patients with residual lesions, analysis of physical parameters showed a significant increase (p < 0.05) in the time necessary for the temperature to rise. In conclusion, this study confirms risk factors of recurrence such as the size of the tumor and emphasizes other factors such as a posttreatment enhanced ring and an increase in the time necessary for the rise in temperature. These factors should be taken into consideration when performing RFA and during follow-up.

Combination of radiofrequency ablation with antiangiogenic therapy for tumor ablation efficacy: study in mice

PURPOSE

To prospectively determine whether modulation of renal cell carcinoma (RCC) tumor microvasculature by using the antiangiogenic drug sorafenib could increase the extent of radiofrequency (RF)-induced coagulation in an RCC animal tumor model.

MATERIALS AND METHODS

All investigations received animal care and utilization committee approval. RCC (human 786-0) was implanted subcutaneously into 27 nude mice. Sixteen mice were randomly assigned into one of three groups when tumors reached 12 mm in diameter: Six mice received 80 mg of sorafenib, a Raf kinase and vascular endothelial growth factor receptor inhibitor, per kilogram of body weight; five mice received 20 mg/kg sorafenib; and five mice received a control carrier vehicle alone. Antiangiogenic therapy was administered until a mean 1-mm reduction in tumor diameter was noted in one group. These 16 mice received a standard dose of RF ablation. Ablation size was visualized by using 2% triphenyltetrazolium chloride. An additional 11 tumors in mice treated with sorafenib alone were stained with CD31 to determine microvascular density (MVD). Resultant size of ablation was compared among groups; statistical significance was determined with analysis of variance. Differences in MVD were assessed with the Kruskal-Wallis test.

RESULTS

Over the 9-day administration of sorafenib, mean tumor size in the control group reached 15.2 mm +/- 0.8 (standard deviation). Tumors in mice receiving 20 mg/kg and 80 mg/kg sorafenib measured 12.2 mm +/- 0.6 and 11.1 mm +/- 0.5, respectively (P < .05). RF-induced coagulation diameter was 8.5 mm +/- 0.4 and 11.1 mm +/- 0.3 in the 20 mg/kg and 80 mg/kg sorafenib groups, respectively, but was only 6.7 mm +/- 0.7 for animals that underwent RF ablation alone (P < .01). Likewise, significant decreases in MVD were noted in the sorafenib-treated animals (P < .01).

CONCLUSION

Treatment of RCC in nude mice with the antiangiogenic agent sorafenib resulted in markedly decreased MVD and significantly larger zones of RF-induced coagulation necrosis.

Influence de la proximité des gros vaisseaux sur les résultats du traitement des carcinomes hépato-cellulaires par radiofréquence : une étude contrôlée

PURPOSE

To evaluate the risk of radiofrequency ablation treatment failure for hepatocellular carcinomas (HCC) next to large vessels.

MATERIALS AND METHODS

Between May 2000 and October 2002, from a total of 83 patients treated by radiofrequency ablation for HCC in a single center, 13 patients with tumor<or=3.5 cm contacting a vessel >or=3 mm in diameter (Group A) were matched with 13 patients with similar size tumors located away from large vessels (Group B). Immediate response and recurrence rate were evaluated on CT.

RESULTS

After mean follow-up interval of 39+/-16.5 months for Group A and 39+/-14 months for Group B, local recurrence rates were 7/12 versus 1/12 respectively (p=0.03). For Group A, 6/7 local recurrences clearly contacted a large vessel.

CONCLUSION

The cooling effect from flowing blood in large vessels markedly increases the rate of local failure of radiofrequency ablation for small HCC located near large vessels.

Injectable polymer depot combined with radiofrequency ablation for treatment of experimental carcinoma in rat

OBJECTIVE

The purpose of this study was to investigate whether an intralesional chemotherapy depot with or without a chemosensitizer could improve the efficacy of radiofrequency (RF) ablation in treatment of experimental carcinoma in rats.

MATERIALS AND METHODS

Eighteen BD-IX rats were inoculated with bilateral subcutaneous tumors via injection of DHD/K12TRb rat colorectal carcinoma cells in suspension. Four weeks after inoculation, one tumor in each rat was treated with RF ablation at 80 degrees C for 2 minutes and the other with RF ablation followed by intralesional chemotherapy with carboplatin. The drug was administered via 2 different in situ-forming poly(D,L-lactide-coglycolide) (PLGA) depot formulations either with or without a chemosensitizer. Treatment efficacy was assessed by comparing the change in tumor diameter compared with control, percent of coagulation necrosis and a rating of treatment completeness.

RESULTS

Tumors treated with ablation and carboplatin + sensitizer (n = 9) showed a diameter decrease of 49.4 +/- 24.5% at the end point relative to ablation control, while those treated with ablation and carboplatin only (n = 8) showed a 7.1 +/- 12.6% decrease. Use of sensitizer also showed increased tissue necrosis (81.9 +/- 9.7% compared with 68.7 +/- 26.7% for ablation only) and double the number of complete treatments (6/9 or 66.7%) compared with ablation control (3/9 or 33.3%).

CONCLUSIONS

From these results, we conclude that intralesional administration of a carboplatin and sensitizer-loaded polymer depot after RF ablation has the potential to improve the outcome of ablation by increasing effectiveness of local adjuvant chemotherapy in preventing progression of tumor unaffected by the ablation treatment.

The safety and efficacy of radiofrequency and electrolytic ablation created adjacent to large hepatic veins in a porcine model

INTRODUCTION

Immediately adjacent to large hepatic veins, tumour ablation by radiofrequency or electrolysis may be impaired by heat or current sink effects. Ablation may also cause vessel injury and thrombosis. The aim of this study was to evaluate the safety and efficacy of radiofrequency and electrolytic ablative techniques adjacent to large hepatic veins.

METHODS

Electrolytic and radiofrequency zones of ablation were created adjacent to hepatic veins in large white pigs. After 72 h the zones of ablation created were examined histologically for (a) the extent of tissue necrosis up to the vessel and (b) the presence of intimal damage and mural thrombus in the veins.

RESULTS

An unexpected complication of electrolysis near large veins was cardiac tamponade. This current related phenomenon could easily be avoided. In seven of nine electrolysis zones of ablation necrosis was completely adjacent to the vessel wall, but in only four of seven radiofrequency zones of ablation. All zones of ablation were associated with intimal necrosis, and most with mural thrombosis.

CONCLUSIONS

Ablation of hepatic tumours by radiofrequency and electrolysis is unreliable adjacent to hepatic veins. Both techniques are associated with mural thrombus formation, and so risk thrombo-embolic complication. These ablative modalities are not recommended for zones of ablation adjacent to hepatic veins.

Image-guided multipolar radiofrequency ablation of liver tumours: initial clinical results

The local effectiveness and clinical usefulness of multipolar radiofrequency (RF) ablation of liver tumours was evaluated. Sixty-eight image-guided RF sessions were performed using a multipolar device with bipolar electrodes in 53 patients. There were 45 hepatocellular carcinomas (HCC) and 42 metastases with a diameter < or =3 cm (n = 55), 3.1-5 cm (n = 29) and >5 cm (n = 3); 26 nodules were within 5 mm from large vessels. Local effectiveness and complications were evaluated after RF procedures. Mean follow-up was 17 +/- 10 months. Recurrence and survival rates were analysed by the Kaplan-Meier method. The primary and secondary technical effectiveness rate was 82% and 95%, respectively. The major and minor complication rate was 2.9%, respectively. The local tumour progression at 1- and 2-years was 5% and 9% for HCC nodules and 17% and 31% for metastases, respectively; four of 26 nodules (15%) close to vessels showed local progression. The survival at 1 year and 2 years was 97% and 90% for HCC and 84% and 68% for metastases, respectively. Multipolar RF technique creates ablation zones of adequate size and tailored shape and is effective to treat most liver tumours, including those close to major hepatic vessels.

Hepatic tumor ablation with clustered microwave antennae: the US Phase II trial

BACKGROUND

Thermal ablation techniques have become important treatment options for patients with unresectable hepatic malignancies. Microwave ablation (MWA) is a new thermal ablative technique that uses electromagnetic energy to produce coagulation necrosis. We report outcomes from the first clinical trial in the United States using MWA and a 915 MHz generator.

PATIENTS AND METHODS

Patients with unresectable primary or metastatic liver cancer were enrolled in a multi-institutional trial from March 2004 through May 2006. Demographic information, diagnosis, treatment, and outcomes were documented.

RESULTS

Eighty-seven patients underwent 94 ablation procedures for 224 hepatic tumors. Forty-two ablations (45%) were performed open, 7 (7%) laparoscopically, and 45 (48%) percutaneously. The average tumor size was 3.6 cm (range 0.5-9.0 cm). Single antenna ablation volumes were 10.0 ml (range 7.8-14.0 ml), and clustered antennae ablation volumes were 50.5 ml (range 21.1-146.5 ml). Outcome variables were measured with a mean follow-up of 19 months. Local recurrence at the ablation site occurred in 6 (2.7%) tumors, and regional recurrence occurred in 37 (43%) patients. With a mean follow-up of 19 months, 41 (47%) patients were alive with no evidence of disease. There were no procedure-related deaths. The overall mortality rate was 2.3%.

CONCLUSIONS

Microwave ablation is a safe and effective technology for hepatic tumor ablation. In our study, clustered antennae resulted in larger ablation volumes. Further studies with histological confirmation are needed to verify clinical results.

Liver transplantation for solitary hepatocellular carcinoma less than 3 cm in diameter in Child A cirrhosis

Liver transplantation for hepatocellular carcinoma (HCC) is the treatment of choice for patients with unresectable tumors within the Milan criteria associated with Child B or C cirrhosis. Liver transplantation provides the best cure for both the HCC and the underlying cirrhosis. In recent years, some authors have advocated liver transplantation even for resectable early HCC associated with Child A cirrhosis, leading to a controversy of whether resection or transplantation should be the first-line therapy for patients with small HCC in Child A cirrhosis. Recent studies comparing liver resection and transplantation for early HCC demonstrated similar long-term survival of 60-70%, but liver transplantation is associated with a lower tumor recurrence rate. However, the current shortage of deceased donor liver grafts limits the applicability of liver transplantation for HCC. The use of live donor liver transplantation for patients with a small solitary HCC in Child A cirrhosis that is resectable may not be justified ethically because of the potential risk to the donors. Patients put on a transplantation waiting list run a significant risk of tumor progression and dropout, while liver resection is immediately applicable to all. Advocating primary liver transplantation for patients with early HCC associated with compensated cirrhosis will increase the waiting time for transplantation and further increases the chance of dropout. Resection first and salvage transplantation for recurrent tumors or liver failure is an alternative strategy that may reduce the use of liver grafts. However, the long-term survival result of such a strategy compared with primary liver transplantation remains unclear.

Single hepatocellular carcinoma ranging from 3 to 5 cm: radiofrequency ablation or resection?

BACKGROUND

The optimal therapy for hepatocellular carcinoma (HCC) is transplantation. For all those patients not eligible for transplantation (or on the waiting list) among the treatments of choice used more frequently in recent years are resection (RES) and radiofrequency ablation (RFA). RFA is less efficacious for HCC ranging over 3 cm. The aim of this study was to compare RFA to RES in a restricted cohort of patients with a single naive HCC ranging from 3 to 5 cm in size and without end-stage liver disease. PATIENTS AND METHODS. A total of 102 patients who had never been treated before were enrolled. Those patients whose HCC position would have required too much parenchymal loss at RES (central or close to main vascular structures) were treated with RFA (n=60), and the others underwent RES (n=42). The two groups were similar for HCC size and liver disease status. The outcome was considered in terms of overall survival (OS) and disease-free survival (DFS) calculated by the Kaplan-Meier method. Differences among groups were validated by log-rank test.

RESULTS

The RES group seemed to present a better long-term OS (91%, 57%, and 43% vs 96%, 53%, and 32% at 1, 3, and 5 years, respectively) and DFS (74%, 35%, and 14% vs 68%, 18%, and 0%, respectively) but there was no statistical significance. Age, gender, virus etiology, HCC size and alpha-fetoprotein levels did not correlate with survival. Patients with recurrence within the first 12 months after treatment showed a worse long-term survival (p=0.011). Patients in Child-Pugh class B had poor prognoses compared with those in class A (p=0.047).

CONCLUSION

Even if RES seemed to promise better long-term results, in the medium term this difference had no statistical significance. Survival in this series was more closely related to the stage of the underlying liver disease than to treatment (RES/RFA).

Microwave ablation in a hepatic porcine model: correlation of CT and histopathologic findings

BACKGROUND

Thermal ablative techniques have gained increasing popularity in recent years as safe and effective options for patients with unresectable solid malignancies. Microwave ablation has emerged as a relatively new technique with the promise of larger and faster burns without some of the limitations of radiofrequency ablation (RFA). Here we study a new microwave ablation device in a living porcine model using gross, histologic, and radiographic analysis.

MATERIALS AND METHODS

The size and shape of ablated lesions were assessed using six pigs in a non-survival study. Liver tissue was ablated using 2, 4, and 8 min burns, in both peripheral and central locations, with and without vascular inflow occlusion. To characterize the post-ablation appearance, three additional pigs underwent several 4 min ablations each followed by serial computed tomography (CT) imaging at 7, 14, and 28 days postoperatively.

RESULTS

The 2 and 4 min ablations resulted in lesions that were similar in size, 33.5 cm(3) and 37.5 cm(3), respectively. Ablations lasting 8 min produced lesions that were significantly larger, 92.0 cm(3) on average. Proximity to hepatic vasculature and inflow occlusion did not significantly change lesion size or shape. In follow-up studies, CT imaging showed a gradual reduction in lesion volume over 28 days to 25-50% of the original volume.

DISCUSSION

Microwave ablation with a novel device results in consistently sized and shaped lesions. Importantly, we did not observe any significant heat-sink effect using this device, a major difference from RFA techniques. This system offers a viable alternative for creating fast, large ablation volumes for treatment in liver cancer.

Percutaneous radiofrequency thermal ablation for hepatocellular carcinoma

BACKGROUND

Radiofrequency thermal ablation is the first therapeutic option in percutaneous treatment of hepatocellular carcinoma but data on its long-term efficacy and safety are not conclusive.

AIM

This study reports a prospective survey on radiofrequency thermal ablation in north-east Italy.

METHODS

Data were collected on 401 patients with hepatocellular carcinoma (males 301, mean age: 68 years) treated by radiofrequency thermal ablation in 13 centres. Indication to treatment was: single nodule not eligible for surgery in 77% of patients, 2-3 nodes in 18% and multiple lesions in 5%. Mean size was 3 cm (1-8 cm). Treatment response was assessed at 1 month by spiral computerized tomography and then with ultrasound examination and new spiral computerized tomography.

RESULTS

Complete response was obtained in 67% of patients and in 27% response was 75-99%. Complete response raised to 77% in lesions smaller than 3 cm. The morbidity rate was 34%; the mortality was 0.5%, seeding was observed in four patients. Ten patients presented an unexpected rapid disease progression.

CONCLUSION

The above data show that by radiofrequency thermal ablation, complete response can be achieved only in about two-third of the cases, clearly less than expected, and that, beyond seeding, unexpected progression can be observed.

Intraoperative triple antenna hepatic microwave ablation

OBJECTIVE

Microwave ablation is emerging as a new treatment option for patients with unresectable hepatic malignancies. This two-center study shows the results of a phase 1 clinical trial of patients with known hepatic masses who underwent synchronous triple antenna microwave ablation before elective hepatic resection.

SUBJECTS AND METHODS

Intraoperative microwave ablation was performed before hepatic resection. Hepatic lesions were targeted using real-time intraoperative sonography with three microwave antennas positioned in a triangular configuration. Microwave ablation was performed at 45 W for 10 minutes. Hepatic resection was then completed in the standard fashion. Gross specimens were sectioned and measured to determine tumor and ablation sizes. Representative areas were stained with H and E stain and vital histochemical nicotinamide adenine dinucleotide (NADH) stain.

RESULTS

Ten patients with a mean age of 64 years (range, 48-79 years) were treated. Tumor histology included colorectal carcinoma metastases and hepatocellular carcinoma. The mean maximal tumor diameter was 4.4 cm (range, 2.0-5.7 cm). The mean maximal ablation diameter was 5.5 cm (range, 5.0-6.5 cm), while the average ablation zone volume was 50.8 cm3 (range, 30.3-65.5 cm3). Gross and microscopic examinations of areas after microwave ablation showed clear coagulation necrosis, even surrounding large hepatic vessels (> 3 mm in diameter). A marked thermallike effect was observed with maximal intensity closest to the antenna sites. NADH staining confirmed the uniform absence of viable tumor in the ablation zone.

CONCLUSION

This study shows the feasibility of using multiple microwave antennas simultaneously in the treatment of liver tumors intraoperatively. Additional percutaneous studies are currently under way to investigate the safety and efficacy in treating nonsurgical candidates.

Impact of incidentally found hepatocellular carcinoma on the outcome of living donor liver transplantation

Hepatocellular carcinoma (HCC) nodules newly found in the explant liver have been observed, but the impact on patient prognosis is not known. Sixty HCC patients who underwent living donor liver transplantation were the subjects of the study. Radiologic findings prior to transplantation and pathologic findings of the explant liver were compared. Histologic characteristics of preoperatively overlooked tumors were examined. The influence of the discrepancy between these findings on tumor recurrence was evaluated. A total of 227 HCC nodules were found in the explant livers. Of these, 91 nodules (40%) were newly found by pathologic examination. They were smaller and more likely to be well differentiated than the others. The number and size of the tumors were underestimated in 50% (30/60) and 32% (19/60), respectively. There was no significant difference in the recurrence-free survival rate between patients who met the Milan criteria both in the pre- and post-transplant evaluation (n = 29) and those who met the Milan criteria preoperatively, but exceeded the criteria in the explant (n = 19). Nodules newly found in the explant liver had little impact on recurrence-free survival. A decision for liver transplantation according to the Milan criteria based on preoperative evaluation is valuable for securing an excellent outcome.

Completeness of treatment in hepatocellular carcinomas treated with image-guided tumor therapies: Evaluation of positive predictive value of contrast-enhanced CT with histopathologic correlation in the explanted liver specimen

OBJECTIVE

To evaluate the positive predictive value of contrast-enhanced multiphase computed tomography (CT) in determining the completeness of treatment, after radiofrequency (RF) ablation and/or transcatheter arterial chemoembolization, based on histopathologic correlation in the explanted liver specimen.

MATERIALS AND METHODS

During a recent 10-year period, 84 consecutive patients who had a history of RF ablation and/or transcatheter arterial chemoembolization for hepatocellular carcinoma (HCC) underwent liver transplantation in our institution. Among them, we selected the patients in whom complete treatment had been considered at periodic follow-up CT (29 tumors in 20 patients, M:F = 18:2, mean age, 47.2 years). The mean size of the tumor at the initial CT was 2.2 cm (range, 0.7-3.6 cm). We investigated the necrosis rate of HCC on the basis of microscopic examinations of the explanted liver specimen and calculated the positive predictive value of CT in determining the completeness of treatment.

RESULTS

The last CT examinations had been obtained 1-37 days before surgery. The overall necrosis rate of HCC for both RF ablation and transcatheter arterial chemoembolization on microscopic examination was 92.9% +/- 12.3%. The positive predictive value of contrast-enhanced CT in determining completeness of treatment was 69.0% (20/29). The tumor necrosis rate for the RF ablation-only group (n = 12) was 91.5% +/- 15.2% with a positive predictive value of 58.3% (7/12) and that of the transcatheter arterial chemoembolization-only group (n = 11) was 91.4% +/- 19.2% with a positive predictive value of 72.7% (8/11).

CONCLUSIONS

Our results suggest that contrast-enhanced CT is limited in accurately determining the completeness of treatment after image-guided tumor ablation for HCC.

Contemporary management of benign hepatic adenoma using percutaneous radiofrequency ablation

Hepatic adenoma is a benign liver tumor that occurs primarily in women. Complete resection of the adenoma is the standard therapy. The authors present an unusual case report of a histologically proven benign hepatic adenoma occurring in an adolescent boy treated with percutaneous radiofrequency ablation (RFA). A 13-year-old adolescent boy presenting with complaints of back pain was incidentally found to have a 3.5 x 2.5-cm solitary hyperechoic region in the liver on ultrasound. Magnetic resonance imaging scan revealed a lobular solid mass in the posterior segment of the right lobe of the liver that did not have the classic appearance of a hemangioma. An ultrasound-guided percutaneous core biopsy of the lesion was performed. Histologic examination revealed a benign liver adenoma. The tumor was treated with RFA by the interventional radiologist. Postprocedure computed tomography scans obtained at 6 weeks, 8 months, and 1 year and magnetic resonance imaging scan obtained 2 years after the procedure showed complete ablation of the tumor with no evidence of tumor recurrence. Traditionally, surgical resection has been the mainstay of therapy for the treatment of benign hepatic adenoma. In selected cases of histologically proven hepatic adenoma, minimally invasive techniques such as RFA can be safely used as an alternative to open surgical resection.

Improved tumor destruction with arsenic trioxide and radiofrequency ablation in three animal models

PURPOSE

To assess the extent of tumor blood flow reduction that is achievable with arsenic trioxide (As2O3) and the effect of As2O3 on radiofrequency (RF)-induced coagulation.

MATERIALS AND METHODS

All animal protocols and experiments were approved by an institutional animal care and use committee before the start of the study. Experiments were conducted in three tumor models: intrarenal VX2 sarcoma in 27 rabbits, RCC 786-0 human renal cell carcinoma in 24 nude mice, and R3230 mammary adenocarcinoma in 40 rats. One dose (0-7.5 mg per kilogram of body weight) of As2O3 was administered (intraperitoneally in rodents, intravenously in rabbits) 1, 6, or 24 hours before standardized RF ablation, which was performed by using a 1-cm active tip, with mean temperatures of 70 degrees C +/- 2 (standard deviation) for 5 minutes in rodents and 90 degrees C +/- 2 for 6 minutes in rabbits. Laser Doppler flowmetry was used to quantify changes in blood flow, which were compared with diameters of induced tumor coagulation. Comparisons between groups were performed by using Student t tests or analysis of variance. The strengths of correlations between As2O3, tumor blood flow, and RF-induced coagulation were assessed by using linear and higher-order regression models and reported as R2 computations.

RESULTS

Administration of As2O3 significantly (P < .05) reduced blood flow and increased tumor destruction in all tumor models. In VX2 sarcoma tumors, 1 mg/kg As2O3 reduced mean tumor blood flow to 46% +/- 13 of the normal value. The mean resultant coagulation (1.1 cm +/- 0.1) was significantly greater than that achieved with RF ablation alone (0.6 cm +/- 0.1, P < .01). In RCC 786-0 and R3230 tumors, 5 mg/kg As2O3 reduced mean tumor blood flow to 57% +/- 6 and 46% +/- 6 of normal, respectively, increasing mean ablation extent to 0.8 cm +/- 0.1 for both models, compared with those achieved with the control treatment (0.6 cm +/- 0.1 and 0.5 cm +/- 0.1, respectively; P < .05 for both comparisons). Dose studies revealed correlations between drug dose, tumor blood flow, and RF-induced coagulation in all three tumor models (R2 = 0.60-0.79). Maximal RF synergy was observed 1 hour after As2O3 administration.

CONCLUSION

As2O3 administration represents a transient noninvasive method of reducing tumor blood flow during RF ablation, enabling larger zones of tumor destruction in multiple tumor models.

Microwave Ablation: Results with a 2.45-GHz Applicator in ex Vivo Bovine and in Vivo Porcine Liver

PURPOSE

To characterize the relationship between applied power and treatment duration in their effect on extent of coagulation produced with a 2.45-GHz microwave applicator in both an ex vivo and a perfused in vivo liver model.

MATERIALS AND METHODS

All experimentation was approved by the Institute of Animal Care and Use Committee. Multiple tissue ablations were performed in ex vivo bovine liver (120 ablations) and in vivo porcine liver (45 ablations) with a 5.7-mm-diameter 2.45-GHz microwave applicator. The applied power was varied from 50 to 150 W (in 25-W increments ex vivo and 50-W increments in vivo), while treatment duration varied from 2 to 20 minutes (in eight time increments for ex vivo and five for in vivo liver). Three-dimensional contour maps of the resultant short- and long-axis coagulation diameters were constructed to identify the optimal parameters to achieve maximum coagulation in both ex vivo and in vivo models. Multivariate analysis was performed to characterize the relationship between applied power and treatment duration.

RESULTS

Power and treatment duration were both associated with coagulation diameter in a sigmoidal fashion (ex vivo, R(2) = 0.78; in vivo, R(2) = 0.74). For ex vivo liver, the maximum short-axis coagulation diameter (7.6 cm +/- 0.2 [standard deviation] by 12.3 cm +/- 0.8) was achieved at greatest power (150 W) and duration (20 minutes). In vivo studies revealed a sigmoidal relationship between duration and coagulation size, with a relative plateau in coagulation size achieved within 8 minutes duration at all power levels. After 8 minutes of treatment at 150 W, the mean short-axis coagulation diameter for in vivo liver was 5.7 cm +/- 0.2 by 6.5 cm +/- 1.7, which was significantly larger than the corresponding result for ex vivo liver (P < .05).

CONCLUSION

Large zones of ablation can be achieved with the 2.45-GHz microwave applicator used by the authors. For higher-power ablations, larger zones of coagulation were achieved for in vivo liver than for ex vivo liver with short energy applications, a finding previously not seen with other ablation devices, to the authors' knowledge.

Effects of Vascular Perfusion on Coagulation Size in Radiofrequency Ablation of Ex Vivo Perfused Bovine Livers

OBJECTIVES

A standardized perfused ex vivo bovine liver model was used to evaluate the effect of organ perfusion on coagulation size and energy deposition during radiofrequency ablation (RFA) procedures.

MATERIALS AND METHODS

Bovine livers were perfused in a tank after rinsing the prepared liver vessels with anticoagulants. Tyrode's solution, oxygenated and heated to 36.5 degrees C, was used as perfusion medium. A flow and pressure controlled pump regulated Portal vein circulation; a dialysis machine provided pulsatile arterial circulation. Impedance-guided radiofrequency ablations were performed with 4-cm LeVeen electrodes with and without underlying liver perfusion. Two-dimensional diameters (Dv, Dh) of each ablation area were measured after dissecting the livers.

RESULTS

In 4 bovine livers weighing 8.85 +/- 0.83 kg per organ (min, 7.7 kg; max, 9.7 kg) altogether 40 RF ablations were performed. A total of 20 ablations were generated with underlying liver perfusion (group 1) and 20 ablations with no liver perfusion (group 2). In group 1, Dv was 28.4 +/- 5.3 mm, Dh 38.6 +/- 7.8 mm, and energy deposition 36.9 +/- 18.0 kJ. The 20 ablation areas generated without liver perfusion displayed statistically significant differences, with Dv being 35.7 +/- 6.5 mm (P = 0.001), Dh 49.5 +/- 9.4 mm (P = 0.001), and energy deposition 25.5 +/- 13.0 kJ (P = 0.018).

CONCLUSION

The model reproduced the cooling effect of perfused tissue during RFA. The ablation areas produced under perfusion conditions had smaller diameters despite longer exposure times and higher energy deposition.