Percutaneous radiofrequency ablation of liver metastases in potential candidates for resection: the "test-of-time approach"

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.

Radiofrequency thermal ablation of liver tumors

Radiofrequency ablation (RFA) of liver tumors was first proposed in 1990. New technologies enable us to produce liver thermal lesions of approximately 3-3.5 cm in diameter; RFA has consequently become an emerging percutaneous therapeutic option both for small hepatocellular carcinoma (HCC) and for non-resectable liver metastases, mainly from colorectal cancer. New devices (for example, triplet of cooled needles, wet needles) and combined therapies (tumor ischemia and RFA) have made it possible to treat large tumors. RFA can be carried out by a percutaneous, laparoscopic or laparotomic approach. Percutaneous RFA can be performed with local anaesthesia and mild sedation; deep sedation or general anaesthesia are also used. The guidance system is generally represented by ultrasound. CT or MR examinations are the more sensitive tests for assessing therapeutic results. The series of patients treated with RFA allow the technique to be considered as effective and safe, achieving a relatively high rate of cure in properly selected cases; it should be classified as curative/effective treatment for HCC, replacing percutaneous ethanol injection. The complication rate of RFA is low but not negligible; key elements in a strategy to minimize them are identified.

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.

Treatment of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignant tumours worldwide. The major etiologies and risk factors for HCC development are well defined and some of the multiple steps involved in hepatocarcinogenesis have been elucidated in recent years. Despite these scientific advances and the implementation of measures for early HCC detection in patients at risk, patient survival has not improved during the last three decades. This is due in part to the advanced stage of the disease at the time of clinical presentation, in part due to the limited therapeutic options. These fall into four main categories: (1) surgical interventions, including tumour resection and liver transplantation, (2) percutaneous interventions, including ethanol injection and radiofrequency thermal ablation, (3) transarterial interventions, including embolisation and chemoembolisation and (4) drugs as well as gene and immune therapies. These therapeutic strategies have been evaluated in part in randomised controlled clinical trials that are the basis for therapeutic recommendations. While surgery and percutaneous as well as transarterial interventions are effective in patients with limited disease (1-3 lesions, < 5 cm in diameter) and compensated underlying liver disease (cirrhosis Child A), at the time of diagnosis more than 80% patients present with multicentric HCC and advanced liver disease or comorbidities that restrict the therapeutic measures to best supportive care. In order to reduce morbidity and mortality from HCC, therefore, early diagnosis and the development of novel systemic therapies for advanced disease, including drugs, gene and immune therapies as well as primary HCC prevention are of paramount importance. Further, secondary HCC prevention after successful therapeutic interventions needs to be improved in order to make an impact on the survival of patients with HCC. New technologies, including gene expression profiling and proteomic analyses, should further elucidate the molecular events underlying HCC development and identify novel diagnostic markers as well as therapeutic and preventive targets.

An unusual presentation of a malignant jejunal tumor and a different management strategy

Background

Malignant small bowel tumors are very rare and leiomyosarcoma accounts for less than 15% of the cases. Management of these tumors is challenging in view of nonspecific symptoms, unusual presentation and high incidence of metastasis. In this case report, an unusual presentation of jejunal sarcoma and management of liver metastasis with radiofrequency ablation (RFA) is discussed.

Case presentation

A 45-year-old male presented with anemia and features of small bowel obstruction. Operative findings revealed a mass lesion in jejunum with intussusception of proximal loop. Resection of bowel mass was performed. Histopathological findings were suggestive of leiomyosarcoma. After 3-years of follow-up, the patient developed recurrence in infracolic omentum and a liver metastasis. The omental mass was resected and liver lesion was managed with radiofrequency ablation.

Conclusion

Jejunal leiomyosarcoma is a rare variety of malignant small bowel tumor and a clinical presentation with intussusception is unusual. We suggest that an aggressive management approach using a combination of surgery and a newer technique like RFA can be attempted in patients with limited metastatic spread to liver to prolong the long-term survival in a subset of patients.

[Contrast ultrasound imaging in focal liver lesions: diagnostic value and guidelines]

The recent introduction of high quality scanners and contrast agents for ultrasound deeply modifies diagnosis strategy in focal liver lesions by using validated criteria. Non-linear imaging methods using low mechanical index (MI<0.2) and second generation contrast agents allow real-time continuous imaging with concomitant limitation in background tIssue signal and also in agent collapse for a high quality contrast imaging giving dramatic improvement in detection and characterization of lesions. Interpretation is based on the presence of contrast agent within the lesion or not (hyper-, hypo- or isosignal) and the delay after injection (arterial, portal or parenchymal or late phase) as previously used by non-ultrasound methods. This allows an easy differentiation of benign from malignant lesions. Moreover, this allows complete characterization in 85 to 95% of all focal liver lesions and 75% in hepatocellular carcinomas. Those results markedly improve ultrasound accuracy compared to conventional sonography and so put contrast-enhanced sonography among recommended non-invasive imaging methods for focal liver lesions with changes in diagnostic strategy according to the lesion type and actual place of US methods. It is recommended to use contrast ultrasound methods in cancer staging for an optimal detection of liver metastases as well as in characterization of lesions detected during conventional sonography with a consecutive decrease of cost-diagnosis ratio.

Complications After Percutaneous Saline-Enhanced Radiofrequency Ablation of Liver Tumors: 3-Year Experience with 336 Patients at a Single Center

OBJECTIVE

Our objective was to report the complications that occurred in a large series of patients with primary or metastatic liver tumors treated with percutaneous saline-enhanced radiofrequency ablation under sonographic guidance at a single center during 3 years of experience.

SUBJECTS AND METHODS

Between September 2000 and October 2003, 336 consecutive patients (221 men and 115 women; age range, 44-78 years; mean, 67 years) with 407 malignant liver tumors were treated at our institution using radiofrequency ablation. Of these patients, 287 had hepatocellular carcinoma from cirrhosis, 47 had liver metastases (38 from colon, six from breast, two from lung, and one from cutaneous melanoma), and two had primary cholangiocarcinoma. Adverse events related to radiofrequency ablation were prospectively recorded.

RESULTS

The number of sessions performed was 375 (39 patients had two sessions). The number of patients with major complications, including death, was three (0.9%). The overall mortality rate was 0.3% (1/336). One patient died because of worsening liver decompensation. Two other major complications occurred. In one patient (0.3%), liver abscess and sepsis developed and were successfully treated with percutaneous sonography-guided needle (18-gauge) aspiration and IV antibiotics. Mild posttreatment ascites occurred in one patient (0.3%). One patient showed self-limiting subcutaneous cellulitis along the electrode-needle path that healed in 2 weeks. Fever lasting 1-3 days and pain lasting 12-24 hr were observed in 141 patients (42%) and 211 patients (63%), respectively. So far, no cutaneous or abdominal wall seeding has been observed clinically or sonographically.

CONCLUSION

Radiofrequency ablation of liver tumors can be considered safe. Life-threatening acute liver failure can be considered a rare possible complication.

Detection of liver metastases: gadobenate dimeglumine-enhanced three-dimensional dynamic phases and one-hour delayed phase MR imaging versus superparamagnetic iron oxide-enhanced MR imaging

The aim of this study was to compare the diagnostic performance of gadobenate dimeglumine (Gd-BOPTA)-enhanced MR imaging, including dynamic phases and one-hour delayed phase, versus superparamagnetic iron oxide (SPIO)-enhanced imaging for detection of liver metastases. Twenty-three patients with 59 liver metastases underwent Gd-BOPTA-enhanced MR imaging (unenhanced, arterial, portal, equilibrium and one-hour delayed phase) using three-dimensional volumetric interpolated imaging and SPIO-enhanced T2-weighted turbo spin-echo and T2*-weighted gradient-echo sequences on a 1.5-T unit. Three observers independently interpreted the three sets of images, i.e. Gd-BOPTA-enhanced dynamic MRI (set 1), delayed phase imaging (set 2) and SPIO-enhanced MRI (set 3). Diagnostic accuracy was evaluated using the alternative-free response receiver operating chracteristic (ROC) analysis. Sensitivity and positive predictive value were also evaluated. The mean accuracy (Az values) and sensitivity of Gd-BOPTA-enhanced delayed phase imaging (0.982, 95.5%) were comparable to those of SPIO-enhanced imaging (0.984, 97.2%). In addition, Az values and sensitivities of both imaging sets were significantly higher than those of Gd-BOPTA-enhanced dynamic images (0.826, 77.4%: p<0.05). There was no significant difference in the positive predictive value among the three image sets. Gd-BOPTA-enhanced delayed phase imaging showed comparable diagnostic performance to SPIO-enhanced imaging for the detection of liver metastases, and had a better diagnostic performance than Gd-BOPTA-enhanced dynamic images.

Hepatocellular carcinoma treated with interventional procedures: CT and MRI follow-up

In the past decade, a variety of interventional procedures have been employed for local control of hepatocellular carcinoma (HCC). These include transcather arterial chemoembolization (TACE) and several tumour ablation techniques, such as percutaneous ethanol injection (PEI), radio-frequency ablation (RFA), or percutaneous microwave coagulation therapy (PMC), laser-induced interstitial thermotherapy (LITT), etc. For a definite assessment of the therapeutic efficacy of interventional procedures, histological examination using percutaneous needle biopsy may be the most definite assessment of the therapeutic efficacy of interventional therapy, however, it is invasive and the specimen retrieved does not always represent the entire lesion owing to sampling errors. Therefore, computed tomography (CT) and magnetic resonance imaging (MRI) play a crucial role in follow-up of HCC treated by interventional procedures, by which the local treatment efficacy, recurrent disease and some of therapy-induced complications are evaluated. Contrast enhanced axial imaging (CT or MR imaging) may be the most sensitive test for assessing the therapeutic efficacy. The goal of the review was to describe the value of CT and MRI in the evaluation of interventional treatments.

Metastatic Colorectal Carcinoma: Cost-effectiveness of Percutaneous Radiofrequency Ablation versus That of Hepatic Resection

PURPOSE

To evaluate the relative cost-effectiveness of radiofrequency (RF) ablation and hepatic resection in patients with metachronous liver metastases from colorectal carcinoma (CRC) and compare the outcomes, cost, and cost-effectiveness of a variety of treatment and follow-up strategies.

MATERIALS AND METHODS

A state-transition decision model for evaluating the (societal) cost-effectiveness of RF ablation and hepatic resection in patients with CRC liver metastases was developed. The model tracks the presence, number, size, location, growth, detection, and removal of up to 15 individual metastases in each patient. Survival, quality of life, and cost are predicted on the basis of disease extent. Imaging, ablation, and resection affect outcomes through detection and elimination of individual metastases. Several patient care strategies were developed and compared on the basis of cost, effectiveness, and incremental cost-effectiveness (expressed as dollars per quality-adjusted life-year [QALY]). Extensive sensitivity analysis was performed to evaluate the impact of alternative scenarios and assumptions on results.

RESULTS

A strategy permitting ablation of up to five metastases with computed tomographic (CT) follow-up every 4 months resulted in a gain of 0.65 QALYs relative to a no-treat strategy, at an incremental cost of $2400 per QALY. Compared with this ablation strategy, a strategy permitting resection of up to four metastases, one repeat resection, and CT follow-up every 6 months resulted in an additional gain of 0.76 QALYs at an incremental cost of $24 300 per QALY. Across a range of model assumptions, more aggressive treatment strategies (ie, ablation or resection of more metastases, treatment of recurrent metastases, more frequent follow-up imaging) were superior to less aggressive strategies and had incremental cost-effectiveness ratios of less than $35 000 per QALY. Findings were insensitive to changes in most model parameters; however, results were somewhat sensitive to changes in size thresholds for RF ablation, the number of metastases present, and surgery and treatment costs.

CONCLUSION

RF ablation is a cost-effective treatment option for patients with CRC liver metastases. However, in most scenarios, hepatic resection is more effective (in terms of QALYs gained) than RF ablation and has an incremental cost-effectiveness ratio of less than $35 000 per QALY.

Radio-frequency ablation of colorectal liver metastases in 167 patients

The objective of this paper is to report our results from a prospective study of 167 patients with colorectal liver metastases treated with radio-frequency ablation (RFA). Three hundred fifty-four treatments were performed in 167 patients, 99 males, mean age 57 years (34-87). The mean number of metastases was 4.1 (1-27). The mean maximum diameter was 3.9 cm (1-12). Fifty-one (31%) had stable/treated extra-hepatic disease. Treatments were performed under general anaesthesia using US and CT guidance and single or cluster water-cooled electrodes (Valleylab, Boulder, CO). All patients had been rejected for or had refused surgical resection. Eighty percent received chemotherapy. Survival data were stratified by tumour burden at the time of first RFA. The mean number of RFA treatments was 2.1 (1-7). During a mean follow-up of 17 months (0-89), 72 developed new liver metastases and 71 developed progressive extra-hepatic disease. There were 14/354 (4%) major local complications and 22/354 (6%) minor local complications. For patients with < or =5 metastases, maximum diameter < or =5 cm and no extra-hepatic disease, the 5-year survival from the time of diagnosis was 30% and from the time of first thermal ablation was 26%. Given that the 5-year survival for operable patients is a median of 32%, our 5-year survival of 30% is promising.

Radiofrequency ablation for metastatic hepatic tumor in colorectal carcinoma

PURPOSE

The purpose of this study was to assess the efficacy and safety of radiofrequency ablation (RFA) to treat hepatic metastasis in patients with colorectal carcinoma.

MATERIALS AND METHODS

Between May 1999 and July 2002, a total of 45 tumors in 24 patients with colorectal cancer were treated with RFA. Thirteen patients received systemic chemotherapy after the RFA procedure. The ablation was performed percutaneously under ultrasound guidance using cool-tip or expandable electrodes and an RF generator. The medical records as well as the CT scan results taken every 3 months were retrospectively reviewed.

RESULTS

The median follow-up duration of the surviving patients was 11.7 months (4.6 approximately 32.2 months). Complete tumor necrosis was achieved in 17 patients (70.8%) on an immediate (<24 hrs) CT scan. The median survival was 17.1 months. The 1- and 2-year survival rates were 80.5 and 25.8%, respectively. In a univariate analysis, complete necrosis, tumor size and post-RFA chemotherapy were significant factors for survival. Nineteen of the 24 patients developed a recurrence or progressed (79.2%). The median progression free survival was 5.5 months. There were no treatment related deaths or serious adverse effects, with the exception of one case of respiratory failure.

CONCLUSION

These results suggest that RFA is a well-tolerated and effective method to treat hepatic metastasis in colorectal carcinomas.

Tea polyphenol (-)-epigallocatechin-3-gallate inhibits DNA methyltransferase and reactivates methylation-silenced genes in cancer cell lines

Hypermethylation of CpG islands in the promoter regions is an important mechanism to silence the expression of many important genes in cancer. The hypermethylation status is passed to the daughter cells through the methylation of the newly synthesized DNA strand by 5-cytosine DNA methyltransferase (DNMT). We report herein that (-)-epigallocatechin-3-gallate (EGCG), the major polyphenol from green tea, can inhibit DNMT activity and reactivate methylation-silenced genes in cancer cells. With nuclear extracts as the enzyme source and polydeoxyinosine-deoxycytosine as the substrate, EGCG dose-dependently inhibited DNMT activity, showing competitive inhibition with a K(i) of 6.89 microM. Studies with structural analogues of EGCG suggest the importance of D and B ring structures in the inhibitory activity. Molecular modeling studies also support this conclusion, and suggest that EGCG can form hydrogen bonds with Pro(1223), Glu(1265), Cys(1225), Ser(1229), and Arg(1309) in the catalytic pocket of DNMT. Treatment of human esophageal cancer KYSE 510 cells with 5-50 microM of EGCG for 12-144 h caused a concentration- and time-dependent reversal of hypermethylation of p16(INK4a), retinoic acid receptor beta (RARbeta), O(6)-methylguanine methyltransferase (MGMT), and human mutL homologue 1 (hMLH1) genes as determined by the appearance of the unmethylation-specific bands in PCR. This was accompanied by the expression of mRNA of these genes as determined by reverse transcription-PCR. The re-expression of RARbeta and hMLH1 proteins by EGCG was demonstrated by Western blot. Reactivation of some methylation-silenced genes by EGCG was also demonstrated in human colon cancer HT-29 cells, esophageal cancer KYSE 150 cells, and prostate cancer PC3 cells. The results demonstrate for the first time the inhibition of DNA methylation by a commonly consumed dietary constituent and suggest the potential use of EGCG for the prevention or reversal of related gene-silencing in the prevention of carcinogenesis.

Percutaneous ablation of liver tumours

The goal of local ablation treatment of hepatic disease is to prolong survival for patients with unresectable tumours. Presently, influence on survival is difficult to estimate because of the heterogeneity of indications and treatments and short follow-up. This chapter therefore focuses on potential benefits and limitations, complications and solutions for improvement. The main problems with in situ ablation are the lack of good imaging techniques to determine the extent of disease and the lack of a method for real-time monitoring of irreversible tissue effect. With one exception, there are no prospective, randomized studies comparing local destruction methods. It appears that percutaneous ethanol injection and cryotherapy should be replaced by radiofrequency ablation (RFA) or interstitial laser thermotherapy (ILT) and that there is little difference in outcome between RFA and ILT. Intraoperative RFA or ILT is valuable as an adjunct to hepatic resection in order to increase the rate of resectability. The percutaneous approach needs further development. It might be valuable in a few truly unresectable or inoperable patients or in selected patients with neuroendocrine liver metastases. In the large majority of unresectable patients it should, however, presently be used and evaluated only in prospective, randomized studies.

Radiofrequency thermal ablation: Correlation of hyperacute MR lesion images with tissue response

PURPOSE

To investigate the hypothesis that the outer boundary of the hyperintense region observed in hyperacute (several minutes post-ablation) T2 and gadolinium contrast-enhanced (CE) T1-weighted magnetic resonance (MR) lesion images is an accurate predictor of eventual cell death from radiofrequency (RF) thermal ablation.

MATERIALS AND METHODS

A low-field, open MR imaging system was used to guide an ablation electrode into a thigh muscle of five rabbits and acquire in vivo T2 and CE T1-weighted MR volumes. Ablation occurred by applying RF current for two minutes with the electrode's temperature maintained at 90 degrees +/- 2 degrees C. After fixation, we sliced and photographed the tissue at 3 mm intervals, using a specially designed apparatus, to obtain a volume of tissue images. Digital images of hematoxylin and eosin (H&E) and Masson trichrome-stained histologic samples were obtained, and distinct regions of tissue damage were labeled using a video microscopy system. After the MR and histology images were aligned using a three-dimensional registration method, we compared tissue damage boundaries identified in histology with boundaries marked in MR images.

RESULTS

The lesions have distinct zones of tissue damage histologically: a central zone of necrotic cells surrounded by an outer zone with cells that appeared non-viable and associated with marked interstitial edema. In 14 histology images from five lesions, the inner and outer boundaries of the outer zone were compared with the boundaries of a hyperintense rim that surrounds a central hypointense region in the T2 and CE T1-weighted MR images. For T2 and CE T1-weighted MR images, respectively, the mean absolute distance was 1.04 +/- 0.30 mm (mean +/- SD) and 1.00 +/- 0.34 mm for the inner boundaries, and 0.96 +/- 0.34 mm and 0.94 +/- 0.44 mm for the outer boundaries. The mean absolute distances for T2 and CE T1-weighted MR images were not sufficiently different to achieve statistical significance (P = 0.745, 0.818, for the inner and outer boundary, respectively).

CONCLUSION

In hyperacute T2 and CE T1-weighted MR lesion images, observations strongly suggest that the outer boundary of the hyperintense rim corresponds to the region of eventual cell necrosis within a distance comparable to our ability to measure. This is good evidence that during RF ablation procedures, MR lesion images can be used to accurately localize the zone of irreversible tissue damage at the lesion margin.