Hepatic resection in stage IV colorectal cancer: prognostic predictors of outcome

Streamline flow of the portal vein affects the lobar distribution of colorectal liver metastases and has a clinical impact on survival

Purpose

It is believed that blood from the superior mesenteric vein and splenic vein mixes incompletely in the portal vein and maintains a streamline flow influencing its anatomic distribution. Although several experimental studies have demonstrated the existence of streamlining, clinical studies have shown conflicting results. We investigated whether streamlining of portal vein affects the lobar distribution of colorectal liver metastases and estimated its impact on survival.

Methods

Data of patients who underwent hepatectomy for colorectal liver metastases were retrospectively collected. The chi-square test was used for analyzing the distribution of metastasis. Cox analysis was used to identify risk factors of survival. Fisher exact test was used for subgroup analysis comparing hepatic recurrence.

Results

A total of 410 patients were included. The right-to-left ratio of liver metastases were 2.20:1 in right-sided colon cancer and 1.39:1 in left-sided cancer (P = 0.017). Cox analyses showed that margin < 5 mm (P < 0.001; 95% confidence interval [CI], 1.648–4.884; hazard ratio [HR], 2.837), age ≥ 60 years (P = 0.004; 95% CI, 1.269–3.641; HR, 2.149), N2 status (P < 0.001, 95% CI, 1.598–4.215; HR, 2.595), tumor size ≥ 45 mm (P = 0.014; 95% CI, 1.159–3.758; HR, 2.087) and other metastasis (P = 0.012; 95% CI, 1.250–5.927; HR, 2.722) were risk factors of survival. However, in 70 patients who underwent right hemihepatectomy for solitary metastasis, left-sided colorectal cancer was a risk factor (P = 0.019; 95% CI, 1.293–17.956; HR, 4.818), and was associated with higher recurrence than right-sided cancer (43.1% and 15.8%, respectively, P = 0.049).

Conclusion

This study showed significant difference in lobar distribution of liver metastases between right colon cancer and left colorecral cancer. Furthermore, survival of left-sided colorectal cancer was poorer than that of right-sided cancer in patients who underwent right hemihepatectomy for solitary metastasis. These findings can be helpful for clinicians planning treatment strategy.

Increased Duration of Heating Boosts Local Drug Deposition during Radiofrequency Ablation in Combination with Thermally Sensitive Liposomes (ThermoDox) in a Porcine Model

Introduction

Radiofrequency ablation (RFA) is used for the local treatment of liver cancer. RFA is effective for small (<3cm) tumors, but for tumors > 3 cm, there is a tendency to leave viable tumor cells in the margins or clefts of overlapping ablation zones. This increases the possibility of incomplete ablation or local recurrence. Lyso-Thermosensitive Liposomal Doxorubicin (LTLD), is a thermally sensitive liposomal doxorubicin formulation for intravenous administration, that rapidly releases its drug content when exposed to temperatures >40°C. When used with RFA, LTLD releases its doxorubicin in the vasculature around the zone of ablation-induced tumor cell necrosis, killing micrometastases in the ablation margin. This may reduce recurrence and be more effective than thermal ablation alone.

Purpose

The purpose of this study was to optimize the RFA procedure used in combination with LTLD to maximize the local deposition of doxorubicin in a swine liver model. Pigs were anaesthetized and the liver was surgically exposed. Each pig received a single, 50 mg/m² dose of the clinical LTLD formulation (ThermoDox®). Subsequently, ablations were performed with either 1, 3 or 6 sequential, overlapping needle insertions in the left medial lobe with total ablation time of 15, 45 or 90 minutes respectively. Two different RFA generators and probes were evaluated. After the final ablation, the ablation zone (plus 3 cm margin) was dissected out and examined for doxorubicin concentration by LC/MS and fluorescence.

Conclusion

The mean Cmax of plasma total doxorubicin was 26.5 μg/ml at the end of the infusion. Overall, increased heat time from 15 to 45 to 90 minutes shows an increase in both the amount of doxorubicin deposited (up to ~100 μg/g) and the width of the ablation target margin to which doxorubicin is delivered as determined by tissue homogenization and LC/MS detection of doxorubicin and by fluorescent imaging of tissues.

Optimal management of colorectal liver metastases in older patients: a decision analysis

BACKGROUND

Comparative trials evaluating management strategies for colorectal cancer liver metastases (CLM) are lacking, especially for older patients. This study developed a decision-analytic model to quantify outcomes associated with treatment strategies for CLM in older patients.

METHODS

A Markov-decision model was built to examine the effect on life expectancy (LE) and quality-adjusted life expectancy (QALE) for best supportive care (BSC), systemic chemotherapy (SC), radiofrequency ablation (RFA) and hepatic resection (HR). The baseline patient cohort assumptions included healthy 70-year-old CLM patients after a primary cancer resection. Event and transition probabilities and utilities were derived from a literature review. Deterministic and probabilistic sensitivity analyses were performed on all study parameters.

RESULTS

In base case analysis, BSC, SC, RFA and HR yielded LEs of 11.9, 23.1, 34.8 and 37.0 months, and QALEs of 7.8, 13.2, 22.0 and 25.0 months, respectively. Model results were sensitive to age, comorbidity, length of model simulation and utility after HR. Probabilistic sensitivity analysis showed increasing preference for RFA over HR with increasing patient age.

CONCLUSIONS

HR may be optimal for healthy 70-year-old patients with CLM. In older patients with comorbidities, RFA may provide better LE and QALE. Treatment decisions in older cancer patients should account for patient age, comorbidities, local expertise and individual values.

Hepatectomy and resection of concomitant extrahepatic disease for colorectal liver metastases--a systematic review

BACKGROUND

Recent data suggest that hepatectomy for patients with colorectal liver metastases (CLM) with concomitant extrahepatic disease (EHD) achieve encouraging survival result. The authors examine the clinical efficacy of this treatment approach through a systematic review of the published literature.

METHODS

Electronic search of the MEDLINE and PubMed databases (January 2000 to January 2011) to identify studies reporting outcomes of hepatectomy for CLM with resection of EHD was undertaken. Two reviewers independently appraised each study using a predetermined protocol. Clinical efficacy was synthesised through a narrative review with full tabulation of results of all included studies.

RESULTS

Twenty-two studies were examined. This comprised 1142 patients. The median disease-free survival was 12 (range, 4-22) months, median overall survival was 30 (range, 14-44) months and median 5-year survival rate was 19% (range, 0-42%). Median 5-year survival of patients with R0 hepatectomy with resection of EHD was 25% (range, 19-36%). Survival based on site of EHD include lung; median survival (M/S) was 41 (range, 32-46) months, porto-caval lymph node; M/S was 25 (range, 19-48) months, peritoneal metastases; M/S was 25 (range, 18-32) months.

CONCLUSION

In the era of effective systemic therapies, surgical resection of CLM and concomitant EHD in carefully selected patients may achieve survival results superior to non-surgically treated patients. This treatment strategy may be considered appropriate especially when a R0 hepatectomy and complete resection of EHD may be achieved.

Prognostic factors in survival of colorectal cancer patients with synchronous liver metastasis

AIM

To determine the factors affecting the survival in colorectal cancer patients with synchronous liver metastases.

METHOD

A total of 168 patients who had been treated colorectal cancer with synchronous liver metastases at Guangxi Medical University from January 2000 to December 2005 were identified. Criteria studied consisted of gender, age, time of symptoms, primary tumour location, primary tumour circumference, histological type, grade (tumour differentiation), T-status, N-status, large bowel obstruction, type of operation, primary tumour resection, ascities, location, number and diameter of liver lesions, preoperative CEA and chemotherapy. Survival curves were plotted using the Kaplan-Meier method. Multivariate analysis was conducted by Cox regression analysis.

RESULTS

The mean survival time for all patients was 18.71 (SEM = 1.59) months. The 1, 2, 3 and 5-year survival rates were 55.95%, 23.21%, 12.30%, 8.0% respectively. Univariate analysis share of grade (tumour differentiation), N-status, large bowel obstruction, operation, primary tumour resection, location, number and the most diameter of liver lesions, extrahepatic transfer, preoperative CEA level and chemotherapy to be predictors of survival. In the Cox regression analysis, the N-status, large bowel obstruction, operation, diameter of liver lesion and extrahepatic transfer were independent factors related to survival.

CONCLUSION

Tumour differentiation, N-status, bowel obstruction, operation, primary tumour resection, location of liver metastasis, number of liver metastasis, diameter of liver metastasis, extrahepatic transfer, preoperative CEA level and chemotherapy are related to the survival of patients with colorectal cancer and synchronous liver metastases.

Management of the hepatic lymph nodes during resection of liver metastases from colorectal cancer: a systematic review

BACKGROUND

Hepatic lymph node involvement is generally considered a contraindication for liver resection performed for colorectal liver metastases. However, some advocate hepatic lymphadenectomy in the presence of macroscopic involvement and others routine lymphadenectomy. The aim of this review is to assess the role of lymphadenectomy in resection of liver metastases from colorectal cancer.

METHODS

Medline, Embase and Central databases were searched using a formal search strategy. Trials with survival data with a minimum follow-up of 1 year were considered for inclusion. Meta-analysis was performed using Revman.

RESULTS

A total of 4230 references were identified. Ten reports of nine studies including 926 patients qualified for the review. The prevalence of nodal metastases after routine lymphadenectomy was 16.3%. The overall 3-year and 5-year survival rates in node-positive patients were 9/151 (11.3%) and 2/137 (1.5%), respectively, compared to 3-year and 5-year survival rates of 424/787 (53.9%) and 246/767 (32.1%) in node-negative patients. The odds ratios for 3-year and 5-year survivals in node positive disease compared to node-negative disease were 0.12 (95% CI 0.06 to 0.24) and 0.08 (95% CI 0.03 to 0.22). There was no randomized controlled trial which assessed the survival benefit of routine or "selective" lymphadenectomy.

CONCLUSION

Currently, there is no evidence of survival benefit for routine or selective lymphadenectomy. Survival rates are low in patients with positive lymph nodes draining the liver irrespective of whether they are detected by routine lymphadenectomy or by macroscopic involvement. Further trials in this patient group are required.

Surgical resection versus non-surgical treatment for hepatic node positive patients with colorectal liver metastases

BACKGROUND

Involvement of hepatic lymph node in patients with colorectal liver metastases is associated with poor prognosis.

OBJECTIVES

To determine the benefits and harms of curative liver resection with lymphadenectomy versus other treatments for colorectal liver metastases with hepatic node involvement.

SEARCH STRATEGY

We searched The Cochrane Hepato-Biliary Group Controlled Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, MEDLINE, EMBASE, Science Citation Index Expanded, and LILACS until September 2009 for identifying the randomised trials.

SELECTION CRITERIA

We considered only randomised clinical trials (irrespective of language, blinding, or publication status) comparing liver resection (alone or in combination with radiofrequency ablation or cryoablation) versus other treatments (neo-adjuvant chemotherapy, chemotherapy, or radiofrequency ablation) in patients with colorectal liver metastases with hepatic node involvement.

DATA COLLECTION AND ANALYSIS

Two authors independently identified trials for inclusion.

MAIN RESULTS

We were unable to identify any randomised clinical trial fulfilling the inclusion criteria of this review. We were also unable to identify any quasi-randomised or cohort studies, which could meaningfully answer this important issue.

AUTHORS' CONCLUSIONS

There is no evidence in the literature to assess the role of surgery versus other treatments for patients with colorectal liver metastases with hepatic node involvement. High quality randomised clinical trials are feasible and are necessary to determine the optimal management of patients with colorectal liver metastases with hepatic node involvement.

Systematic review of tumour number and outcome after radical treatment of colorectal liver metastases

Background

Resection of colorectal liver metastases (CLMs) is potentially curative but the effect of tumour number on prognosis is uncertain. This study compared the prognosis after resection and/or ablation of between one and three, or four or more CLMs.

Methods

A systematic literature review from January 2000 to June 2008 was performed. Study selection and data extraction were standardized, and analysis included assessment of methodological quality, heterogeneity and bias. Main outcomes were 3- and 5-year survival. A meta-analysis comparing radical treatment in the two groups was performed using the hazard ratio for overall survival.

Results

Of 1307 studies screened, 46 (9934 patients) were included in the analysis. Methodological quality was variable, and there was significant heterogeneity and reporting bias. The overall 5-year survival rate after radical treatment ranged from 7 to 58 per cent. Pooled hazard ratio for overall survival was 1·67 (95 per cent confidence interval 1·43 to 1·95; P &lt; 0·001). Median reported 5-year survival for patients with four or more CLMs was 17·1 per cent.

Conclusion

Radical treatment of more than three CLMs results in poorer overall survival. Nevertheless, 5-year survival is achievable and the number of lesions should not, of itself, be used to exclude patients from surgery.

Synchronous colorectal liver metastases: is it time to reconsider traditional paradigms of management?

BACKGROUND

Patients with synchronous colorectal liver metastases (CLM) are typically treated with initial colorectal resection followed by arbitrary and prolonged courses of chemotherapy. Partial hepatectomy is considered only for patients without interval disease progression. This review describes the rationale for this treatment approach and the recent developments suggesting that this management paradigm should be reconsidered.

RESULTS

Because asymptomatic colorectal cancer often does not lead to complications, and given the potential benefit of chemotherapy in downsizing unresectable to resectable liver disease, most patients with asymptomatic primary tumors and unresectable synchronous CLM should be first treated with chemotherapy. In contrast, initial hepatic resection should be considered for resectable synchronous CLM. Survival benefits from prehepatectomy chemotherapy have not been established. Several reports demonstrate morbidity after hepatic resection from extended durations of irinotecan- and/or oxaliplatin-based prehepatectomy chemotherapy. Although shorter treatment periods may not have these deleterious effects on subsequent hepatic resection, prospective studies reveal that most patients with supposedly aggressive disease with short treatment durations will not be identified. Moreover, a complete radiologic response to prehepatectomy chemotherapy is not only rare but also does not equate with a complete pathological response. Finally, several studies suggest that simultaneous colorectal and minor hepatic resections can performed safely with benefits in total morbidity when compared with traditional staged procedures.

CONCLUSIONS

The traditional treatment paradigm centering on the utility of prehepatectomy chemotherapy for resectable synchronous CLM should be reconsidered. Recent developments underscore the need for prospective randomized controlled trials evaluating the optimal timing of hepatectomy relative to chemotherapy.

Resection of colorectal liver metastases: is a resection margin of 3 mm enough? : a multicenter analysis of the GAST Study Group

BACKGROUND

A safety margin of > or =10 mm is generally accepted in surgery for colorectal metastases. It is reasonable that modern methods of liver parenchyma dissection may allow for a reduction in this distance.

METHODS

A total of 333 patients were included in a multicenter trial after resection of colorectal liver metastases. Dissection of the liver had been performed with a CUSA, UltraCision, or water-jet dissector. The size of the resection margin was correlated with recurrence risk and survival.

RESULTS

The median hepatic recurrence-free survival reached 35 months for all patients; median recurrence-free survival was 24 months and overall survival was 41 months. Univariate analysis of different groups denoting the extent of resection margin (> or =10 mm, 6-9 mm, 3-5 mm, 1-2 mm, 0 mm (R1)) indicated that a margin of 1-2 mm leads to a significantly reduced median hepatic recurrence-free survival of 20 months (p = 0.004) and recurrence-free survival of 19 months (p = 0.011). Patients with R1 resection had the worst prognosis. Overall survival was not influenced by the size of the resection margin. Surgical margins were significantly reduced in simultaneous resections of four or more liver metastases and in cases in which metastatic infiltration of central liver segments was present. At multivariate analysis, resection margins of 1-2 mm and 0 mm were independent predictors of hepatic recurrence and overall recurrence.

CONCLUSION

The indication for resection of metastases can be safely extended to cases in which tumors sit closer than 1 cm to nonresectable structures.

Liver resection for colorectal liver metastases in older patients

INTRODUCTION

Seventy-six percentages of patients with a newly diagnosed colorectal carcinoma are between 65 and 85 years old. A substantial proportion will develop liver metastases, for which resection is the only potential curative treatment. This study was conducted to investigate both the feasibility, and short- and long-term outcomes of liver resection for colorectal liver metastases in elderly patients.

METHODS

Between August 1990 and April 2007 data were prospectively collected on patients over 70 years of age who underwent a liver resection for colorectal liver metastases in a single centre.

RESULTS

One hundred and eighty-one liver resections were performed in 178 consecutive patients (median age 74 years). Thirty-four patients (18.8%) received neoadjuvant chemotherapy (all FOLFOX) prior to liver surgery and the majority (57.5%) of liver resections involved more than two Couinaud's segments. Median hospital stay was 13 days, 70 (38.5%) patients had postoperative complications, and overall in hospital mortality was 4.9% (9 patients). Overall- and disease-free survival rates at 1, 3 and 5 years were 86.1%, 43.2% and 31.5% and 65.8%, 26% and 16%, respectively. In multivariate analysis: T3 primary staging; major liver resections; more than three liver lesions; and the occurrence of postoperative complications were associated with inferior overall survival.

CONCLUSIONS

Liver resection for colorectal liver metastases in elderly patients is safe and may offer long-time survival to a substantial percentage of patients. We strongly recommend considering senior patients for surgical treatment whenever possible.

The role of contrast-enhanced ultrasound for focal liver lesion detection: an overview

The development of new ultrasound (US) contrast agents and sonographic techniques has considerably improved the possibilities of ultrasound in the assessment of liver tumors. An overview is given on diagnostic potential of contrast-enhanced US (CEUS) and real-time low mechanical index technique in the detection of various focal liver lesions compared with computed tomography, magnetic resonance imaging or intraoperative US. In two of our own studies that included 100 patients each we showed an increase of correct findings in CEUS compared with B-mode US from 64% to 87% and from 67% to 84% as confirmed by intraoperative evaluation of the liver. Especially after chemotherapy and in the case of small metastases, significantly more metastases were correctly detected by CEUS compared with B-mode US. These results and clinical study results in the literature show that CEUS allows tumor detection and direct visualization of the tumor vascularity and put contrast-enhanced sonography among recommended noninvasive imaging methods for focal liver lesions with improvements in diagnostic strategy.

Major hepatectomy in patients with synchronous colorectal liver metastases: whether or not a contraindication to simultaneous colorectal and liver resection?

OBJECTIVE

Synchronous hepatic lesions account for 15-25% of newly diagnosed colorectal cancer and its optimal timing to surgery is not completely defined, but simultaneous colorectal and liver resection is recently gaining acceptance, at least in patients with a right colonic primary and liver metastases that need a minor hepatectomy to be fully resected.

METHOD

From September 2002 to December 2004, 16 patients underwent simultaneous resection as treatment of synchronous colorectal liver resection; in 10 patients (62.5%) a major hepatectomy was performed.

RESULTS

The mean duration of intervention was 322.5 +/- 59.5 min, operative mortality and morbidity rates was 0% and 25% respectively; the hospitalization was 14.4 (range 8-60) days on average. Mean follow-up was 14 months and actuarial survival was 76.5% at 1 year and 63.5% at 2 years.

CONCLUSION

We concluded that simultaneous colonic and liver resection should be undertaken in selected patients with synchronous colorectal liver resection regardless of the extent of hepatectomy; major liver resection, in fact, seems capable of providing better oncological results, allowing resection of liver micrometastases that, in almost one-third of the patients, are located in the same liver lobe of macroscopic lesions, without increased morbidity rates.

Contrast-enhanced ultrasonography to detect liver metastases : a prospective trial to compare transcutaneous unenhanced and contrast-enhanced ultrasonography in patients undergoing laparotomy

BACKGROUND/AIMS

The advent of contrast-enhanced ultrasound (CEUS) has called into question the efficacy of standard ultrasonographic techniques. In this study, we evaluated B-mode and color-duplex imaging and CEUS in the detection of liver metastases, using intraoperative and histological findings as a reference.

MATERIALS AND METHODS

Before laparotomy, 108 patients suspected of having liver metastases were prospectively examined with B-mode and color-duplex imaging, followed by contrast-enhanced ultrasound (2.4 ml SonoVue). Patients with unresectable tumors (n=8) were excluded from the analysis. The sonographic diagnosis in the remaining 100 patients was compared to the intraoperative and histological findings.

RESULTS/FINDINGS

CEUS improved the sensitivity for detecting liver lesions from 56.3% (B-mode) to 83.8% (CEUS) (p=0.004). In particular, the contrast agent led to an improvement in ultrasonographic detection in the following cases: nodular metastases smaller than one centimeter; after adjuvant chemotherapy; for tumors near the surface of the liver; and for lesions situated around the ligamentum teres.

INTERPRETATION/CONCLUSIONS

CEUS provides significant improvement in the detection of liver metastases, and should therefore, be performed routinely in the surveillance of cancer patients.

Surgical treatment of liver metastases from colorectal cancer in elderly patients

INTRODUCTION

The liver is the most frequent site of liver metastases (LM) from colorectal cancer. Because of short life expectancies and improved nonoperative modalities, the role of liver resection in elderly patients with LM is unclear.

METHODS

During a 15-year period, 197 patients underwent liver resection for colorectal metastases. This study was designed to compare morbidity, mortality, and long-term outcome after hepatic resection in patients aged 70 years and older and in patients younger than 70. According to the age at the time of operation, patients were divided into two groups. Group A included patients aged 70 years or older and group B included younger patients.

RESULTS

The clinical and pathologic parameters of the two groups were compared and tested as factors affecting early and long-term outcomes after resection. A modified oncologic clinical risk score (CRS) was tested on this series of patients. Overall morbidity was 16.3% (group A 20.7% vs group B 14.6%; P=0.18). Hospital mortality was 3% (5.7% in group A and 2.1% in group B; P=0.19). Actuarial 5 years survival were 30% in group A and 38% in group B (P=ns).

DISCUSSION

The presence of more than three Fong's CRS parameters and microscopic involvement of resectional margin directly affected survival. Under meticulous preoperative assessment and postoperative care, liver resection for LM is justified in patients over 70 years of age; age by itself may not be a controindication to surgery.

The treatment of hepatic metastases in colorectal carcinoma

Colorectal carcinoma is the third most common cause of cancer death in the United States, with 135,000 new cases and 55,000 deaths annually. Ultimately, two-thirds (99,000) of all patients with colorectal cancer will develop metastasis to the liver and other organs in their life span, making metastatic colorectal cancer the second leading cause of cancer-related death in North America. The optimal management of these patients has become increasingly complex with the myriad of treatment options that are available. Because the timing of any therapy (surgery, chemotherapy, or others) has become integral to the success of the treatment, a collaborative approach involving multiple specialties is needed for the best patient outcome. Defined clinical and pathologic determinants of outcome have been demonstrated to effect the overall and disease-free survival of patients with metastatic colorectal cancer. Understanding of these determinants remains essential to any treating physician and has lead to significant paradigm shifts in the management of patients with metastatic colorectal cancer.

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.