Comparison of resection and radiofrequency ablation for treatment of solitary colorectal liver metastases

Current status of sonographically guided radiofrequency ablation techniques

OBJECTIVE

The purpose of this article was to review the current clinical applications of sonographically guided radiofrequency ablation (RFA) techniques.

METHODS

Publications regarding RFA extracted from a computerized database (MEDLINE) and from references cited in these articles were reviewed to evaluate the clinical effect and patient outcome.

RESULTS

Radiofrequency ablation has shown some promising effects in the treatment of tumors in various parts of the body. The recent advances in RFA technology enable larger volumes of treatment and make RFA clinically practical. It is most often used for hepatic and renal tumors, and applications for other organs and structures are increasing and rapidly developing. Sonography provides a convenient way to guide and monitor the procedure in most situations.

CONCLUSIONS

Effectiveness of RFA in the treatment of tumors in various body parts has been achieved. Radiofrequency ablation should be considered as an alternative or complementary method in the integration of oncologic management to obtain the greatest benefit to patients.

Rates and patterns of recurrence for percutaneous radiofrequency ablation and open wedge resection for solitary colorectal liver metastasis

INTRODUCTION

The purpose of this study was to compare rates and patterns of disease progression following percutaneous, image-guided radiofrequency ablation (RFA) and nonanatomic wedge resection for solitary colorectal liver metastases.

METHODS

We identified 30 patients who underwent nonanatomic wedge resection for solitary liver metastases and 22 patients who underwent percutaneous RFA because of prior major hepatectomy (50%), major medical comorbidities (41%), or relative unresectability (9%). Serial imaging studies were retrospectively reviewed for evidence of local tumor progression.

RESULTS

Patients in the RFA group were more likely to have undergone prior liver resection, to have a disease-free interval greater than 1 year, and to have had an abnormal carcinoembryonic antigen (CEA) level before treatment. Two-year local tumor progression-free survival (PFS) was 88% in the Wedge group and 41% in the RFA group. Two patients in the RFA group underwent re-ablation, and two patients underwent resection to improve the 2-year local tumor disease-free survival to 55%. Approximately 30% of patients in each group presented with distant metastasis as a component of their first recurrence. Median overall survival from the time of resection was 80 months in the Wedge group vs 31 months in the RFA group. However, overall survival from the time of treatment of the colorectal primary was not significantly different between the two groups.

CONCLUSIONS

Local tumor progression is common after percutaneous RFA. Surgical resection remains the gold standard treatment for patients who are candidates for resection. For patients who are poor candidates for resection, RFA may help to manage local disease, but close follow-up and retreatment are necessary to achieve optimal results.

Local radiofrequency ablation techniques for liver metastases of colorectal cancer

Local ablative techniques have been used for several decades in the treatment of colorectal liver metastases and are gaining more and more interest. At this time radiofrequency ablation is the most popular local ablative technique with interesting results on local tumour control, disease free and overall survival. However, the exact place in the treatment of non-resectable colorectal liver metastases and its possible place in the treatment of resectable liver metastases has still to be defined. This article describes the feasibility, advantages and disadvantages of radiofrequency ablation, together with the results of the most cited articles, to form a critical review on the use of this technique in the treatment of colorectal liver metastases.

Actual role of radiofrequency ablation of liver metastases

The liver is, second only to lymph nodes, the most common site for metastatic disease irrespective of the primary tumour. More than 50% of all patients with malignant diseases will develop liver metastases with a significant morbidity and mortality. Although the surgical resection leads to an improved survival in patients with colorectal metastases, only approximately 20% of patients are eligible for surgery. Thermal ablation and especially radiofrequency ablation emerge as an important additional therapy modality for the treatment of liver metastases. RF ablation shows a benefit in life expectancy and may lead in a selected patient group to cure. Percutaneous RF ablation appears safer (versus cryotherapy), easier (versus laser), and more effective (versus ethanol instillation and transarterial chemoembolisation) compared with other minimally invasive procedures. RF ablation can be performed by a percutaneous, laparoscopical or laparotomic approach, and may be potentially combined with chemotherapy and surgery. At present ideal candidates have tumours with a maximum diameter less than 3.5 cm. An untreatable primary tumour or a systemic disease represents contraindications for performing local therapies. Permanent technical improvements of thermal ablation devices and a better integration of thermal ablation in the overall patient care may lead to prognosis improvement in patients with liver metastases.

A cost-utility analysis of treatments for malignant liver tumours: a pilot project

BACKGROUND

Hepatic resection is the standard treatment for colorectal liver metastases when feasible. Techniques such as radiofrequency ablation (RFA) have been the subject of ongoing research in hopes of achieving a similar survival to that achieved with hepatic resection, but with less morbidity and better quality of life (QOL). The aim was to to generate a hypothesis concerning the cost-utility of various treatments that may be further tested with randomized trials in the future.

PATIENTS AND METHODS

This was a prospective, non-randomized pilot study comparing the cost-utility of hepatic resection, RFA, systemic chemotherapy, and symptom control alone for colorectal liver metastases. All patients with newly diagnosed liver malignancies were eligible. QOL was measured serially with the Health Utilities Index. Costs, in 2001 Canadian dollars, were captured from the viewpoint of society in general.

RESULTS

In all, 40 patients were enrolled in the study: 7 underwent hepatic resection, 7 underwent RFA (sometimes in combination with resection), 20 received systemic chemotherapy, and 6 received symptom control alone. Liver resection appeared to be the most effective approach, with an average benefit of 2.58 QALYs (quality-adjusted life years) compared with 1.95 QALYs for RFA, 1.18 QALYs for chemotherapy, and 0.82 QALYs for symptom control alone, resulting in cost-utility ratios of $7792, $8056, $12,571, and $4788 per QALY, respectively.

DISCUSSION

The cost-utility of hepatic resection and RFA appeared similar even though patients receiving RFA had more advanced disease. The role of RFA is still being defined; however, if long-term survival proves to be promising, then this study lends support to the conduct of randomized controlled trials in the future.

Radiofrequency ablation permits an effective treatment for colorectal liver metastasis

BACKGROUND

Radiofrequency ablation (RFA) has become an important adjunct to modern liver surgery. However, scant knowledge on long-term outcome of RFA for colorectal liver metastasis is available, nowadays.

METHODS

This is a prospective clinical study of patients with liver metastasis of colorectal cancer who were treated by RFA between April 1, 1998, and November 30, 2004. Forty-seven patients with 147 liver metastases were treated with RFA in a total of 70 interventions. A metastasis resection was not feasible in 80% of the interventions. All the patients were followed up at regular intervals with contrast-enhanced computed tomography (CT) and laboratory tests including carcinoembryonic antigen (CEA).

RESULTS

No RFA-related mortality occurred. The median follow-up time after the diagnosis of liver metastasis was 33 months. The RFA-related morbidity was 7%. After the RFA, the expected median overall survival rate is, to date, 39 months. Overall survival rates at 1, 2 and 3 years were 88%, 80% and 57%, respectively. Local recurrence rates reached 8.8% overall and 1.6% for metastasis smaller than 3cm in diameter. No local recurrence occurred for metastasis smaller than 3cm in diameter if treated with the newest RFA device.

CONCLUSIONS

Excellent local tumour control was achieved with radiofrequency ablation of small liver metastasis. The expected overall survival rate of patients with RFA for unresectable or non-resected colorectal liver metastasis improved in comparison with the survival rate reported following the natural course (best supportive care) or chemotherapy. The low local recurrence rate of metastases of less than 3cm challenges the results obtained by the more invasive treatment of conventional liver surgery.

Current role of radiofrequency ablation for the treatment of colorectal liver metastases

BACKGROUND AND METHOD

This paper reviews the current status of radiofrequency ablation in the treatment of colorectal liver metastases. Relevant studies with at least ten patients that reported rates of complete tumour ablation, local recurrence, or survival from 1 to 5 years after treatment were included in the review.

RESULTS AND CONCLUSION

Only six studies that reported at least 3-year survival were identified, with results ranging from 37 to 58 per cent. Some of these figures are promising, given that the patients were considered to have unresectable disease. However, available evidence is limited and hepatic resection remains the standard of care when feasible; radiofrequency ablation cannot be considered an equivalent. Radiofrequency ablation does, however, appear to have a role in treating unresectable disease, and may also be used in conjunction with resection to extend its limits.

Intraoperative magnetic resonance imaging for ablation of hepatic tumors

BACKGROUND

The most significant rise in the use of hepatic ablation has come from image-guided techniques with both computed tomography (CT) and ultrasound (US). The recent development of open-configuration magnetic resonance scanners has opened up an entire new area of image-guided surgical and interventional procedures. Thus the aim of this study was to evaluate the use of intraoperative MRI (iMRI) ablation of hepatic tumors performed by surgeons.

METHOD

Percutaneous iMRI hepatic ablation was performed from January 2003 to February 2005 for control of either primary or secondary hepatic disease.

RESULTS

Eighteen hepatic ablations were performed on 11 patients with a median age of 71 (range: 51-81) years for metastatic colorectal cancer (n = 6), hepatocellular cancer (n = 2), cholangiocarcinoma (n = 2), and metastatic neuroendocrine (n = 1). Median hospital stay was 1 day, with complications occurring in 2 patients. After a median follow up of 18 months, there have been no local ablation recurrences, 5 patients are free of disease, 4 are alive with disease, 1 has died of disease, and 1 has died of other causes.

CONCLUSIONS

Image-guided hepatic ablations represent a useful technique in managing hepatic tumors. Intraoperative MRI represents a new technique with initial success that has been limited to European centers. Further evaluation in U.S. centers has demonstrated iMRI to be useful for certain hepatic tumors that cannot be adequately visualized by US or CT.

Magnetic resonance-guided focused ultrasound surgery (MRgFUS): Ablation of liver tissue in a porcine model

BACKGROUND

Liver surgery is technically demanding and is considered a major procedure with relatively high morbidity rates. Magnetic resonance-guided focused ultrasound surgery (MRgFUS) uses focused ultrasonic energy to create a heat coagulation lesion, which can be achieved in a totally controlled, very accurate manner (<1 mm). The aim of this study was to evaluate the safety and accuracy of non-invasive focal ablation of liver tissue achieved by consecutive MRgFUS sonications.

MATERIALS AND METHODS

Six MRgFUS procedures were performed in five pigs under general anesthesia, with the ExAblate 2000 system (InSightec, Israel). Real-time imaging and temperature mapping (Signa Twinspeed 1.5T, GEHC, USA) enabled the immediate evaluation of the results of each sonication. Different foci were chosen within the liver. These mock lesions were ablated by several sonications, each of them performed during 20-30 s of apnea. Between sonications, the pigs were normally ventilated. The pigs were sacrificed 3-21 days after the procedure and their livers were examined.

RESULTS

The MRgFUS created complete tissue destruction of mock lesions in different areas of the pig's liver. The lesion sizes in each animal varied according to the number of sonications used and the extent of overlap between adjacent sonications. The lesion ranged in size from 1.5 cm x 1.5 cm x 2.0 cm to 5.5 cm x 4.5 cm x 2.0 cm. There was no morbidity.

CONCLUSIONS

MRgFUS under general anesthesia is a safe, completely non-invasive technology for the ablation of liver tissue. Liver tissue can be ablated in a very accurate manner, based on the pre-treatment planning on the MR images. The MR imaging characteristics, including real-time temperature mapping, enable real-time control of every step of the ablation process. Mechanical ventilation with intermittent periods of apnea is a technique that overcomes the problem of the respiratory movements of the liver.

Radiofrequency ablation in patients with primary and secondary hepatic malignancies

The aims of this study were to assess the technical effectiveness of radiofrequency (RF) ablation in patients with primary or secondary hepatic malignancies and to determine survival and complication rates. This was a retrospective analysis of prospectively collected data of patients treated with RF ablation and controlled for recurrence every 3 months by contrast-enhanced computed tomography (CT) or magnetic resonance imaging (MRI). The outcome is compared with a comprehensive review of data published in recent literature. Forty-seven patients underwent 50 RF sessions for the ablation of 73 tumors. Local tumor progression was observed in 11 patients (23%). A tumor sized larger than 30 mm, a tumor load larger than 14 cm3, and a percutaneous approach were associated with a faster time to local tumor progression. At the end of a mean (+/- SD) follow-up period of 11.4 +/- 7.5 months, 39 patients (83%) were alive, including eight patients with recurrent disease. The overall cumulative survival rates at 12 and 24 months were 87% and 70%, respectively. In our center, RF ablation can be safely performed to achieve adequate local control and survival rates. Time to local tumor progression was significantly related to initial size of the tumor and tumor load.

RFA for Liver Tumors: Does It Really Work?

The use of radiofrequency ablation (RFA) is increasing in the treatment of both primary and metastatic hepatic tumors. However, the role of RFA has yet to be clearly defined in patients who are still considered amenable to surgical intervention. Future prospective studies are needed to define whether RFA can be used as an alternative to surgery in certain patient populations. In the interim, radiofrequency ablation technology will continue to advance and serve as both a palliative and potentially curative intervention for individuals with hepatic tumors.

Treatment of hepatic metastases from colorectal cancer: Many doubts, some certainties

About 50% of patients with colorectal cancer (CCR) are destined to develop hepatic metastases during the course of the disease. Surgery is currently the only potentially curative treatment with a five year survival rate after hepatectomy from 26% to 49%. The criteria for resectability are now less rigid than in the past and the tendency to adopt a more aggressive treatment of metastatic lesions is the rule. Systemic infusion chemotherapies based on 5-fluorouracil (5-FU), oxaliplatin (OHP) and irinotecan (CPT-11) are well tolerated and have been shown to be effective in non-operable patients. These regimens allow surgery for patients who are initially not suitable for resection, giving them a probability of survival at five years similar to that of patients operated on at diagnosis. Intra-arterial infusion chemotherapy (HAI) is very effective in inducing objective responses, but is costly, difficult to manage and encumbered by major side effects, so that its application is necessarily limited to centres with specific experience. However, despite the broader criteria and recent advances of chemotherapy, surgery is not possible in most patients. The role of other local therapeutic techniques like cryosurgery (CS) and radiofrequency ablation (RF), alone or combined with surgery or chemotherapy, is not yet established in a multidisciplinary therapeutic approach. Roughly two thirds of patients relapse during the first two years after surgery suggesting appropriate post-operative chemotherapy treatment after hepatic resection may be indicated, but no randomised studies have been published to date. In case of relapse, another hepatectomy should be considered. The role of novel targeted therapies in pre-operative, post-operative and palliative management has yet to be evaluated.

Factors influencing the local failure rate of radiofrequency ablation of colorectal liver metastases

BACKGROUND

The prognosis of patients with colorectal cancer is poor, especially when there is distant metastatic disease. Local ablation of tumor by radiofrequency ablation (RFA) has emerged as a safe and effective new treatment modality, but its long-term efficacy may be hindered by renewed local tumor growth at the site of RFA. The objectives of this study were to identify risk factors for local RFA failure and to define exclusion criteria for RFA treatment of colorectal liver metastases.

METHODS

A total of 199 lesions in 87 patients were ablated with RFA. Factors influencing local failure rates were identified and compared with data from the literature.

RESULTS

The local failure rate was 47.2%, and the average time to local disease progression was 6.5 months. Factors that significantly correlated with increased failure rates were metachronous occurrence of liver metastases, large mean lesion size, and central tumor location.

CONCLUSIONS

Because accurate electrode placement is pivotal in achieving adequate tumor necrosis, RFA should not be performed percutaneously when electrode placement is impaired. We suggest that lesions >5 cm and lesions located near great vessels or adjacent organs should be treated with open RFA, thus allowing vascular inflow occlusion and complete mobilization of the liver. Lesions that are difficult to reach by electrodes should be approached by an open procedure.

[Liver metastases from colorectal cancer. Is the practice of surgery based on the best clinical evidence possible?]

To date, surgical resection remains the only curative treatment for liver metastases from colorectal cancer. However, the evidence supporting this treatment is based on retrospective studies. The lack of level I clinical evidence has stimulated strong interest in identifying the factors predictive of recurrence, and even to use them to create clinical risk scores (assigning one point to each factor for poor prognosis), in which a higher score indicates a poorer prognosis. In the present review, we discuss all these factors, as well as the therapeutic alternatives that improve local disease control. Next, we review all the prospective randomized studies published on this topic, which mainly focus on adjuvant chemotherapy associated with curative surgery with negative margins, with the aim of validating or rejecting this treatment. Lastly, we include the algorithm of the University of California at San Francisco for surgery in liver metastases from colorectal cancer.

Magnetic resonance-guided focused ultrasound surgery (MRgFUS). Four ablation treatments of a single canine hepatocellular adenoma

BACKGROUND

Canine hepatocellular adenomas are benign, well-differentiated, primary hepatic tumors. Surgical resection is technically demanding and is considered a major procedure with relatively high morbidity rates. Magnetic resonance-guided focused ultrasound surgery (MRgFUS) uses focused ultrasonic energy to non-invasively create a heat-coagulated lesion deep within the body. This effect can be achieved in a controlled, accurate manner. The aim of this study was to evaluate the safety, accuracy and efficacy of non-invasive focal ablation of tissue volumes of a canine benign liver tumour by consecutive MRgFUS sonications.

MATERIALS AND METHODS

Four MRgFUS procedures were performed in a 10-year-old, male, mixed large breed dog (45 kg) under general anaesthesia. The exact location and volume of the ablated areas were planned on the MR images. Real-time MR imaging and temperature mapping enabled the immediate evaluation of the effect of each sonication. Different areas were chosen within the tumour. These volumes of tumoral tissue were ablated by multiple sonications. To allow accurate targeting and quality imaging, sonications were performed during 20-30 s of apnoea. Between the sonications the dog was normally ventilated. The dog was operated 21 days after the fourth ablative procedure. The tumour was resected and histopathologically examined.

RESULTS

The MRgFUS created necrosis with contiguous areas of complete tissue destruction within the liver tumour, in full accordance with the planning. A focal thermal injury to the cartilage of the right lower ribs was noted after the fourth treatment. This lesion became infected and was treated surgically. Ten months after the last treatment the dog is well and healthy.

CONCLUSIONS

Focused ultrasound ablation of liver tumoral tissue with MR guidance under general anaesthesia and controlled apnoea is a safe and accurate treatment modality. Its main advantage is that it is a completely non-invasive image-guided treatment. The ablation of significant volumes of a highly vascular liver tumoral tissue was achieved. Such tissue can be ablated in a very accurate manner, exactly according to the pretreatment planning on the MR images. The MR imaging characteristics, including real-time temperature mapping, enable real-time control of every step of the ablation process. Mechanical ventilation with intermittent apnoea periods overcomes the problem of the respiratory movements of the liver. Care must be taken to avoid the passage of the ultrasound beam through energy-absorbing calcified tissue.

Bipolar radiofrequency ablation of liver metastases during laparotomy. First clinical experiences with a new multipolar ablation concept

BACKGROUND AND OBJECTIVE

Radiofrequency ablation (RFA) is a promising method for local treatment of liver malignancies. Currently available systems for radiofrequency ablation use monopolar current, which carries the risk of uncontrolled electrical current paths, collateral damages and limited effectiveness. To overcome this problem, we used a newly developed internally cooled bipolar application system in patients with irresectable liver metastases undergoing laparotomy. The aim of this study was to clinically evaluate the safety, feasibility and effectiveness of this new system with a novel multipolar application concept.

PATIENTS AND METHODS

Patients with a maximum of five liver metastases having a maximum diameter of 5 cm underwent laparotomy and abdominal exploration to control resectability. In cases of irresectability, RFA with the newly developed bipolar application system was performed. Treatment was carried out under ultrasound guidance. Depending on tumour size, shape and location, up to three applicators were simultaneously inserted in or closely around the tumour, never exceeding a maximum probe distance of 3 cm. In the multipolar ablation concept, the current runs alternating between all possible pairs of consecutively activated electrodes with up to 15 possible electrode combinations. Post-operative follow-up was evaluated by CT or MRI controls 24-48 h after RFA and every 3 months.

RESULTS

In a total of six patients (four male, two female; 61-68 years), ten metastases (1.0-5.5 cm) were treated with a total of 14 RF applications. In four metastases three probes were used, and in another four and two metastases, two and one probes were used, respectively. During a mean ablation time of 18.8 min (10-31), a mean energy of 48.8 kJ (12-116) for each metastases was applied. No procedure-related complications occurred. The patients were released from the hospital between 7 and 12 days post-intervention (median 9 days). The post-interventional control showed complete tumour ablation in all cases.

CONCLUSIONS

Bipolar radiofrequency using the novel multipolar ablation concept permits a safe and effective therapy for the induction of large volumes of coagulation in the local treatment of liver metastases.

In-vivo evaluation of a novel bipolar radiofrequency device for interstitial thermotherapy of liver tumors during normal and interrupted hepatic perfusion

BACKGROUND

Only monopolar systems have thus far been available for radiofrequency ablation of liver tumors, whose application is restricted because of the incalculable energy flow, reduction of electrical tissue conduction, and limited lesion size. The aim of this study was to evaluate a novel internally cooled bipolar radiofrequency application device under in vivo conditions and to compare the effect of this system on lesion size when combined with hepatic arterial microembolization or complete hepatic blood flow occlusion.

MATERIALS AND METHODS

In a porcine liver model, RFA (60 W, 12 min) was performed with either normal (n = 12), partially interrupted (arterial microembolization via a hepatic artery catheter n = 12) or completely interrupted hepatic perfusion (Pringle's maneuver, n = 12). RFA parameters (impedance, power output, temperature, applied energy) were determined continuously during therapy. RFA lesions were macroscopically assessed after liver dissection.

RESULTS

Bipolar RFA induced clinical relevant ellipsoid thermal lesions without complications. Hepatic inflow occlusion led to a 4.3-fold increase in lesion volume after arterial microembolization and a 5.8-fold increase after complete interruption (7.4 cm(3)versus 31.9 cm(3)versus 42.6 cm(3), P < 0.01).

CONCLUSIONS

The novel bipolar RFA device is a safe and effective alternative to monopolar RFA-systems. Interrupting hepatic perfusion significantly increases lesion volumes in bipolar RFA. This beneficial effect can also be achieved in the percutaneous application mode by RFA combined with arterial microembolization via a hepatic artery catheter.

[Nonoperative ablation for liver metastases. Possibilities and limitations as a curative treatment]

Under the term "nonoperative ablation" are grouped a number of heterogeneous approaches for the treatment of liver metastases, including laser-induced thermotherapy (LITT), radio-frequency therapy (RF), and cryotherapy. In general these procedures had been intended only for palliative purposes. The establishment of clinically relevant lesion size and a lack of long-term survival data were regarded as main limitations to using them with curative intention. During the last years however, new application systems have demonstrated remarkable results in RF and LITT, and some clinical studies have shown long-term survival in selected patients comparable to that for hepatic resection. We review possibilities and limitations of nonoperative ablation procedures with curative intent, highlighting the histopathological bases of thermal ablation techniques and clinical aspects such as R0 ablation and long-term survival.

Multipolar radiofrequency ablation of hepatic tumors: initial experience

Institutional review board approval and patient informed consent were obtained. Use of a multipolar radiofrequency (RF) ablation device in patients with hepatic malignancy was prospectively evaluated with regard to feasibility, achieved ablation zone size and shape, technical effectiveness, and complications. Nineteen malignant liver tumors were treated with the multipolar resistance-controlled RF ablation system, with which up to three internally cooled bipolar coagulation electrodes can be operated simultaneously. Postinterventional imaging was performed with dynamic contrast material-enhanced magnetic resonance (MR) imaging and MR imaging-based three-dimensional planimetry. Complete tumor destruction was achieved in 18 of 19 tumors. Mean ablation zone volume was 52 mL +/- 45 (standard deviation). Thirteen patients were treated with a percutaneous approach; six, with an intraoperative approach. Maximum ablation size was 91 x 62 x 79 mm with the percutaneous and 73 x 98 x 74 mm with the intraoperative approach. Of the 18 completely evaluable ablation zones, 13 were concentric, two were moderately eccentric, two were eccentric, and one was wedge-shaped. The multipolar RF ablation device achieves large ablation zones and has high technical effectiveness in treating hepatic tumors.

Image guided tumour ablation

Several different technologies have been employed for the local ablation of tissue by thermal techniques. At the present time the most widely favoured technique is radiofrequency ablation (RFA) but developments in other techniques, e.g. microwave may change this. In many countries RFA or percutaneous ethanol injection (PEI) are accepted therapies for patients with Childs Pugh Class A or B cirrhosis and early hepatocellular carcinoma (HCC). Results for RFA in large series of patients with liver metastases from colon cancer are very promising. Five-year survival rates of 26% from the time of first ablation and 30% from the diagnosis of liver metastases for patients with limited (<6, <5 cm) liver disease who are not surgical candidates compares well with post resection series where 5-year survival rates vary between 29% and 39% in operable candidates. Sufficient experience has now been gained in lung and renal ablation to show that these are minimally invasive techniques which can produce effective tumour destruction with a limited morbidity. More novel areas for ablation such as adrenal or pelvic recurrence are being explored.

Percutaneous ultrasound-guided radiofrequency ablation of intrahepatic cholangiocarcinoma

This study evaluated the clinical applications, treatment effects, and complications of percutaneous ultrasound (US)-guided radiofrequency ablation (RFA) of intrahepatic cholangiocarcinoma. Ten patients (6 men and 4 women) with histologically proven cholangiocarcinoma underwent US-guided percutaneous RFA. Tumor diameters ranged from 1.9 to 6.8 cm. There were 12 sessions of RFA for 10 solitary cholangiocarcinomas. Eight patients were treated at a single session and two patients had two treatment sessions. The efficacy of RFA was evaluated using contrast-enhanced dynamic computed tomography 1 month after treatment and then every 3 months. Complete necrosis was defined as lack of contrast enhancement of the treated region. There was complete necrosis in eight tumors. In two patients with large tumors (4.7 and 6.8 cm in diameter), enhancement of residual tissue was observed after RFA treatment, indicating residual tumor. Complete necrosis was seen in all five tumors (100%) with diameters of 3.0 cm or less, two of three tumors (67%) with diameters of 3.1-5.0 cm, and one of two tumors (50%) with diameters of more than 5.0 cm. A large biloma was found in one patient after treatment. No serious complications occurred in the other nine patients. In conclusion, percutaneous RFA is effective and successful in the treatment of intrahepatic cholangiocarcinoma of 3 cm or less and satisfactory for tumors of 3-5 cm. The rate of serious complications after RFA is low. Further follow-up is necessary to determine long-term efficacy.

Local recurrence after hepatic radiofrequency coagulation: multivariate meta-analysis and review of contributing factors

OBJECTIVE

The purpose of this study was to analyze the factors that influence local recurrence after radiofrequency coagulation of liver tumors.

SUMMARY BACKGROUND DATA

Local recurrence rate varies widely between 2% and 60%. Apart from tumor size as an important risk factor for local recurrence, little is known about the impact of other factors.

METHODS

An exhaustive literature search was carried out for the period from January 1, 1990 to January 1, 2004. Only series with a minimal follow-up of 6 months and/or mean follow-up of 12 months were included. Univariate and multivariate meta-analyses were carried out.

RESULTS

Ninety-five independent series were included, allowing the analysis of the local recurrence rate of 5224 treated liver tumors. In a univariate analysis, tumor-dependent factors with significantly less local recurrences were: smaller size, neuroendocrine metastases, nonsubcapsular location, and location away from large vessels. Physician-dependent favorable factors were: surgical (open or laparoscopic) approach, vascular occlusion, general anesthesia, a 1-cm intentional margin, and a greater physician experience. In a multivariate analysis, significantly less local recurrences were observed for small size (P < 0.001) and a surgical (versus percutaneous) approach (P < 0.001).

CONCLUSIONS

Radiofrequency coagulation by laparoscopy or laparotomy results in superior local control, independent of tumor size. The percutaneous route should mainly be reserved for patients who cannot tolerate a laparoscopy or laparotomy. The short-term benefits of less invasiveness for the percutaneous route do not outweigh the longer-term higher risk of local recurrence.

Radiofrequency ablation for malignant liver tumor

Radiofrequency ablation (RFA) has been widely practiced to treat unresectable malignant liver tumors. It has the merits of localized tumor ablation and preservation of maximal normal liver parenchyma. In recent years, there has been a tremendous expansion in the application of RFA for patients with malignant liver tumors. However, the therapeutic effect of this local ablation treatment needs to be balanced against its risks and possible local failure. This review focuses on the current status of RFA for malignant liver tumors, with special attention to the indication, approaches, complications, survival benefits, combination therapies, and comparison with other treatment modalities. Although the results of most clinical studies of RFA seem favorable, the associated risks and tumor recurrence should not be underestimated. Careful patient selection, meticulous RFA techniques, and prompt treatment of residual and recurrent tumors are necessary to ensure a better outcome after RFA. Until recently, there has been no strong evidence showing that RFA can replace any other treatment modalities in the management of liver tumors. Nonetheless, more convincing evidence by randomized trials is required for the establishment of a treatment protocol of RFA for patients with malignant liver tumors.

The use of radiofrequency in cancer

Radiofrequency ablation (RFA) provides an effective technique for minimally invasive tissue destruction. An alternating current delivered via a needle electrode causes localised ionic agitation and frictional heating of the tissue around the needle. Image-guided, percutaneous ablation techniques have been developed in most parts of the body, but the most widely accepted applications are for the treatment of hepatocellular carcinoma (HCC) in early cirrhosis, limited but inoperable colorectal liver metastases, inoperable renal cell carcinoma and inoperable primary or secondary lung tumours. The procedures are well tolerated and the complication rates low. Patients with coexistent morbidity who are not suitable for surgery are often able to undergo RFA. Most treatments in the lung, kidney and for HCC are performed under conscious sedation with an overnight hospital stay or as a day-case. Larger more complicated ablations, for example, in hepatic metastases may require general anaesthesia. Limitations of RFA include the volume of tissue that can be ablated in a timely fashion, that is, most centres will treat 3-5 tumours up to 4-5 cms in diameter. Early series reporting technical success and complications are available for lung and renal ablation. Liver ablation is better established and 5-year survival figures are available from several centres. In patients with limited but inoperable colorectal metastases, the 5-year survival ranges from 26 to 30% and for HCC it is just under 50%. In summary, RFA provides the opportunity for localised tissue destruction of limited volumes of tumour; it can be offered to nonsurgical candidates and used in conjunction with systemic therapy.

Development and validation of an experimental model for the assessment of radiofrequency ablation of pancreatic parenchyma

OBJECTIVES

The aim of this study was to develop and validate an ex vivo model for the assessment of radiofrequency (RF) ablation of the pancreas.

METHODS

Porcine pancreata were used within 1 hour of sacrifice. RF was delivered to a premarked area in the center of the pancreatic head using a thermocouple-tipped multiprobe array. Four temperature presets were evaluated: 70 degrees-100 degrees C in 10 degrees increments. Immediately after ablation serial sections of the pancreatic head were cut to incorporate duodenum, portal vein, and bile duct. For each experiment, a portion of pancreatic tail was sampled as nonablated control. Hematoxylin and eosin (H&E) slides together with nicotinamide adenine dinucleotide (NADH) stained preparations were made. The NADH staining was quantified using computerized digital image recognition techniques.

RESULTS

Control sections (n = 20) demonstrated normal pancreatic architecture on H&E and strong NADH staining indicating preserved tissue oxidative metabolism. RF produced a temperature-dependent destruction of parenchymal architecture (H&E) with a corresponding loss of NADH activity. There was no evidence of thermal injury to the duodenum. Quantification of NADH staining demonstrated a median positive staining of 69.26% (55.87-97.28) for control tissue compared with 1.40% (0-7.77) for ablated pancreas (P < 0.001; Mann-Whitney U test).

CONCLUSION

This study describes the development of a relatively simple, reliable, and reproducible model for evaluation of RF ablation of pancreatic parenchyma.

Optimal cytoreduction after combined resection and radiofrequency ablation of hepatic metastases from recurrent malignant ovarian tumors

BACKGROUND

The role of radiofrequency ablation (RFA) in the treatment of hepatic metastases from recurrent ovarian tumors is undefined.

CASE

Three patients with hepatic lesions from recurrent ovarian cancers underwent a combined partial hepatectomy with radiofrequency ablation (RFA) to achieve optimal tumor cytoreduction. Follow-up radiological studies as well as serial tumor markers are consistent with disease-free survival after 39, 13, and 9 months.

CONCLUSION

These results demonstrate the feasibility and safety of RFA for metastatic ovarian lesions to the liver in patients previously deemed as poor or non-surgical candidates, and suggest the potential for improvement in survival over unresected patients or in patients resected with residual disease.

Management of midgut carcinoids

Midgut carcinoids developing in the small intestine represent the most common cause of the carcinoid syndrome, with severe symptoms of flush, diarrhoea, and fibrotic valvular heart disease. The tumours may be histologically identified with specific chromogranin A or synaptophysine immunostainings, and by serotonin reactivity, which supports a midgut origin. Urinary 5-HIAA excretion and serum chromogranin A measurements are used as biochemical tumour markers for clinical diagnosis, and as important monitors of treatment effects and prognostic predictors. The midgut carcinoids have typically slow proliferation and extended disease course, and surgical treatment has become increasingly important for their management. Surgery should aim to remove primary tumours and mesenteric metastases, which may cause long-term abdominal complications, by typical fibrotic intestinal entrapment and small bowel ischaemia due to encasement of mesenteric vessels. Attempts should also be made to surgically remove or ablate liver metastases, since this may significantly contribute to palliation of the carcinoid syndrome. In patients with this syndrome surgery is combined with continuous biotherapy with long-acting somatostatin analogues and interferon, which may alleviate symptoms and cause stable disease with slow progression. Favourable survival and life-quality can be expected with this treatment also in patients with advanced midgut carcinoids.

Radiofrequency ablation of colorectal liver metastases

BACKGROUND

Untreated patients with colorectal liver metastases rarely survive 3 years, and the 3-year survival rate for patients treated with chemotherapy is 3%. The best survival rates are for the small subgroup that has operable disease, i.e., 39% at 5 years. Radiofrequency ablation (RFA) offers a new opportunity to destroy liver metastases in patients who are not surgical candidates because of disease distribution or comorbidity.

METHODS

Acceptance criteria were a maximum of four or five liver lesions with a maximum diameter of 4 or 5 cm and no evidence of active extrahepatic disease. Nearly all treatments were performed percutaneously using ultrasound, computed tomography, or magnetic resonance imaging (or some combination) for guidance and monitoring. RFA is a minimally invasive procedure that can be readily repeated. General anesthesia facilitates the procedure but is not essential. Multiple overlapping ablations are required to ensure optimal treatment in all but the smallest tumors.

RESULTS

In our cohort of 167 patients with colorectal liver metastases, 73 fulfilled the optimal acceptance criteria (5 or fewer tumors that were </=5 cm). The median survival periods were 38 months, with a 5-year survival rate of 30%, after the diagnosis of liver metastases and 31 months, with a 5-year survival rate of 25%, after the first ablation.

CONCLUSION

RFA increases the therapeutic options for patients with colorectal metastases. Until controlled trials can better define the role of RFA, there are several groups of patients who are not surgical candidates and can be considered for RFA.

Incidence of Unsuspected and Treatable Metastatic Disease Associated With Operable Colorectal Liver Metastases Discovered Only at Laparotomy (and Not Treated When Performing Percutaneous Radiofrequency Ablation)

BACKGROUND

When patients with resectable colorectal liver metastases (LM) are treated with percutaneous radiofrequency (RF), some unsuspected intrahepatic and extrahepatic metastases, detectable only at laparotomy, might be ignored and left untreated. This would result in a reduced cure rate. Our purpose was to discover the incidence of unsuspected and surgically treatable intrahepatic and extrahepatic metastases discovered at laparotomy.

METHODS

The data of 506 patients who underwent a laparotomy and then a hepatectomy for colorectal LM were prospectively collected and retrospectively analyzed. All patients had undergone at least two types of preoperative liver imaging (but no fluorodeoxyglucose-positron emission tomography).

RESULTS

Unsuspected metastases were discovered at laparotomy in 209 patients (41.3%). There were extrahepatic metastases in 82 patients (16.2%), additional LM in 152 patients (30%), and both in 25 patients (4.9%). Liver palpation and intraoperative ultrasound allowed for detecting additional LM in 125 (24.7%) and 48 (9.4%) patients, respectively. All of them were resected. When only the 124 patients who presented with 1 to 3 LM measuring <3 cm in diameter (candidates for percutaneous RF) were considered, the results were similar. Moreover, the incidence of unsuspected metastases was similar when the periods of surgery (before and after January 1996) were considered.

CONCLUSIONS

Laparotomy permits discovery of and treatment with a curative intent of unsuspected intrahepatic or extrahepatic metastases in at least one third of patients with classically resectable colorectal LM. This does not support the use of percutaneous RF ablation instead of hepatic resection for this population, because it will result in an important survival decrease.

What factors influence survival in patients with unresected synchronous liver metastases after resection of colorectal cancer?

OBJECTIVE

The aim of this study was to determine whether the survival of patients with untreated synchronous liver metastases after resection of a colorectal cancer was associated with any features of the primary tumour.

METHODS

Information for 398 consecutive patients with unresected liver metastases in the period 1971-2001 was examined by multivariate survival analysis.

RESULTS

Of 19 clinical and pathological variables considered, survival was independently associated only with residual tumour in a line of resection (hazard ratio (HR) 1.95), venous invasion (HR 1.87), right colonic tumour (HR 1.68), lymph node metastasis (HR 1.54), and extra-hepatic metastasis (HR 1.16); 8.3% of patients had none of these adverse features. Their 2-year overall survival rate was 39.2%, compared with only 16.5% (P < 0.001) in those with one or more adverse features.

CONCLUSIONS

These findings may assist in selecting patients most likely to benefit from treatment of hepatic metastases and in counselling patients and their relatives.

Percutaneous radiofrequency ablation of hepatic colorectal metastases: technique, indications, results, and new promises

Surgical resection is the standard of care for colorectal metastases isolated to the liver. However, only 10-25% of the patients are eligible for resection because of extent and location of the disease in the liver or concurrent medical conditions. Image-guided radiofrequency (RF) ablation is a minimally invasive technique that is emerging as a viable alternate treatment of nonsurgical patients with limited hepatic metastatic disease. Several series have shown that RF ablation can result in complete tumor eradication in properly selected candidates and have provided indirect evidence that the treatment improves survival. In a recent multicenter trial including 423 patients, overall survival of RF-ablation treated patients reached 47% at 3 years and 24% at 5 years. RF ablation technology is undergoing continuous improvement, and its clinical application has been successfully expanded to the treatment of colorectal metastases to the lung. Randomized trials comparing RF ablation with either surgical resection or chemotherapy protocols, however, are still missing. In this article, we review technique, indications, clinical results, and future prospects of RF ablation in the therapeutic management of metastatic colorectal cancer patients.

Prevention and therapy of colorectal cancer

Colorectal cancer is expected to affect more than 146,000 and kill more than 57,000 Americans in 2004. Increased understanding of carcinogenesis is transforming clinical approaches to all stages of this disease. During the last 5 years, four new drugs have been approved for colorectal cancer treatment, and substantial progress has been made in identifying and developing agents that prevent or delay carcinogenesis. These advances substantiate target-driven approaches to cancer prevention and treatment, and provide fruitful opportunities for future investigations.

Noninvasive thermal ablation of hepatocellular carcinoma by using magnetic resonance imaging-guided focused ultrasound

A number of minimally invasive methods have been tested for the thermal ablation of liver tumors as an alternative to surgical resection. The use of focused ultrasound transducers to ablate deep tumors offers the first completely noninvasive alternative to these techniques. By increasing the flexibility of this technology with modern phased-array transducer design and by combining it with magnetic resonance imaging for targeting and online guidance, a powerful tool results with the potential to offer treatment to a larger population of patients, to reduce trauma to the patient, and to reduce the cost of treatment. In this article, we review previous work with focused ultrasound in the liver and recent experimental results with magnetic resonance imaging guidance.

MR appearances of radiofrequency thermal ablation region: histopathologic correlation with dog liver models and an autopsy case

RATIONALE AND OBJECTIVES

The purpose of this study was to evaluate the utility of magnetic resonance (MR) imaging for indicating the extent of true tissue necrosis of the liver after radiofrequency (RF) ablation in comparison with histopathologic findings in dog models and an autopsy case.

MATERIALS AND METHODS

RF ablation of the liver parenchyma was performed on three dogs under general anesthesia. MR appearances of the RF-ablated regions on T1-weighted fast-low angle shot (FLASH; repetition time/echo time [TR/TE]/flip angle: 120/3.8/70),T2-weighted turbo spin echo (3000/80/echo train = 25) and contrast-enhanced T1-weighted images were compared with histopathologic findings. An autopsy case with hepatocellular carcinoma was also enrolled in this study.

RESULTS

All ablated regions showed three zones on T1-weighted FLASH images: a central zone with low intensity, a broad hyperintense middle zone, and a surrounding hypointense band. The central and middle zones corresponded to the degrees of coagulation necrosis observed during histopathologic examination, whereas no viable cells were seen in these zones during the microscopic examination using nicotinamide adenine dinucleotide diaphorase stain. The surrounding hypointense band corresponded to sinusoidal congestion in the acute phase and to fibrotic change in the subacute phase.

CONCLUSION

MR imaging using the FLASH sequence can accurately determine the extent of the necrotic area after RF ablation.