Liver tumor ablation techniques

Utility of intraoperative liver ultrasound

Intraoperative ultrasound has become an essential tool for the surgeon in the field of hepatobiliary surgery. No preoperative study has been able to duplicate the sensitivity and specificity of IOUS in the identification of occult lesions. With recent improvements in technology, IOUS has now become an indispensable means of defining the extent of disease and respectability, and providing a guide to anatomic and nonanatomic hepatic resections and minimally invasive and percutaneous ablative techniques.

Large hepatic ablation with bipolar saline-enhanced radiofrequency: an experimental study in in vivo porcine liver with a novel approach

SUMMARY BACKGROUND DATA

Radiofrequency ablation (RFA) is a relatively new technology for the local destruction of liver tumors. Development of recent devices has enabled the creation of larger lesions. Nevertheless, treating liver tumors larger than 2.5 cm in diameter often requires multiple overlapping ablations to encompass the tumor and the surrounding healthy tissue rim with an increasing risk of local recurrence.

MATERIAL AND METHODS

RFA (480 kHz) of the liver using our method was undertaken on a total number of 15 healthy farm pigs with (Group B, n = 8) or without (Group A, n = 5) the Pringle maneuver via laparotomy. The pigs were followed and euthanized on the seventh day of the experiment. Livers were removed for histological assessment. Time of the procedure, impedance, current, power output, energy output, temperatures in the liver, central temperature of the animal, volume size of the lesion, and delivered energy per lesion volume were determined and compared among groups. Additionally a regularity ratio (RR) was determined by gross examination of the specimen and scored (0-3) taking into account regularity and predictability of the ablation with pathologic assessment.

RESULTS

With both methods, ellipsoid lesions were created between the two probes. In both groups tissue impedance fell with time (r = -0.47, P < 0.01 and r = -0.34, P < 0.05, in Groups A and B, respectively). The mean lesion size achieved with the Pringle maneuver was the largest lesion size described in the literature for any RFA method in vivo and was greater in Group B than in Group A (123.22 cm(3) +/- 49.62 and 52.40 cm(3) +/- 23.59, respectively, P < 0.05). A better regularity and predictability evaluated by RR was observed in Group B compared to Group A (1.88 +/- 1.35 and 0.40 +/- 0.55, respectively, P < 0.05). Five major complications were described and attributed primarily to failure in isolation from hypertermic lesions.

CONCLUSIONS

Our new bipolar saline-enhanced electrode with Pringle maneuver achieves large hepatic ablations in in vivo pig liver. These large lesions are well-tolerated by the animal when thermal injuries to adjacent structures are avoided.

Percutaneous tumor ablation with radiofrequency

BACKGROUND

Radiofrequency thermal ablation (RFA) is a new minimally invasive treatment for localized cancer. Minimally invasive surgical options require less resources, time, recovery, and cost, and often offer reduced morbidity and mortality, compared with more invasive methods. To be useful, image-guided, minimally invasive, local treatments will have to meet those expectations without sacrificing efficacy.

METHODS

Image-guided, local cancer treatment relies on the assumption that local disease control may improve survival. Recent developments in ablative techniques are being applied to patients with inoperable, small, or solitary liver tumors, recurrent metachronous hereditary renal cell carcinoma, and neoplasms in the bone, lung, breast, and adrenal gland.

RESULTS

Recent refinements in ablation technology enable large tumor volumes to be treated with image-guided needle placement, either percutaneously, laparoscopically, or with open surgery. Local disease control potentially could result in improved survival, or enhanced operability.

CONCLUSIONS

Consensus indications in oncology are ill-defined, despite widespread proliferation of the technology. A brief review is presented of the current status of image-guided tumor ablation therapy. More rigorous scientific review, long-term follow-up, and randomized prospective trials are needed to help define the role of RFA in oncology.

Radiofrequency Ablation: A Novel Primary and Adjunctive Ablative Technique for Hepatic Malignancies

The majority of primary and metastatic tumors of the liver are not amenable to surgical resection at presentation. Radiofrequency ablation (RFA) is a new modality for local tumor destruction with minimal local and systemic complications. We prospectively reviewed the experience with RFA at a single institute as a primary or adjunctive ablative technique in the treatment of hepatic malignancies. Between November 1997 and December 1998, 30 patients with primary or metastatic hepatic lesions were treated with RFA at the John Wayne Cancer Institute and the Cancer Center at Century City Hospital. Pathology of the treated lesions included colorectal metastases (29 in 14 patients), neuroendocrine metastases (29 in 4 patients), noncolorectal metastases (29 in 9 patients), and hepatocellular carcinoma (6 in 3 patients). Twelve patients underwent RFA laparoscopically, 12 at celiotomy, and the remaining 6 patients had percutaneous ablation. RFA was the only procedure in 17 patients, whereas the remainder underwent a combination of RFA and other procedures including resection, cryosurgical ablation, and hepatic artery infusion pump placement. Median length of stay for all patients was 6 days (2 days for laparoscopic patients). A single complication of a delayed intrahepatic abscess was noted in this series (3%). There have been no deaths associated with RFA. At a median follow-up of 5 months, 16 patients remain disease free, and 10 are alive with disease. RFA is a safe and effective method of tumor ablation for hepatic malignancies. This technique can be performed laparoscopically, at celiotomy, or percutaneously and can be used as a primary technique or in conjunction with other interventional procedures.

Interstitial laser coagulation for hepatic tumours

BACKGROUND

The potential role of interstitial laser coagulation (ILC) for patients with irresectable hepatic tumours is currently being investigated. Since its introduction in 1983 it has evolved into an innovative minimally invasive technique.

METHODS

On the basis of a Medline literature search and the authors' experience, the principles, current state and prospects of ILC for hepatic tumours are reviewed.

RESULTS

Animal studies and early clinical studies have shown the safety and feasibility of ILC. The site of interest can be approached at laparoscopy or percutaneously and treatment is easily repeatable. Recent advances include the use of fibres with a cylindrical diffusing light-emitting tip, the length of which is adaptable to tumour diameter, water-cooled fibre systems, simultaneous multiple fibre application, and hepatic inflow occlusion during laser treatment. ILC allows complete destruction of tumours up to 5 cm in diameter. Currently a limitation is the lack of reliable real-time monitoring of laser-induced effects but progress in magnetic resonance imaging techniques should allow accurate temperature measurements to be obtained rapidly during treatment. However, the actual benefit of ILC in terms of patient survival remains to be investigated.

CONCLUSION

In terms of tools and experience, ILC has now been developed sufficiently to study its effect on survival of patients with irresectable hepatic tumours.

High-dose mitomycin C in isolated hyperthermic liver perfusion for unresectable liver metastases

In order to reduce systemic side effects and increase intrahepatic mitomycin C (MMC) concentrations, isolated hyperthermic liver perfusion (IHLP) has been performed using MMC. This article describes the pharmacokinetics of MMC in IHLP and presents our clinical experience with its use in six patients suffering from unresectable liver metastases. Primary tumors consisted of colorectal carcinomas in three cases, breast cancer in two, and a choroidal melanoma in one. Dosages of MMC varied between 0.5 and 1.0 mg MMC/kg body weight. MMC was added as a bolus directly into the extracorporeal circuit. Intrahepatic temperature was elevated to 40.0-41.0 degrees C by hyperthermic perfusion. MMC concentrations were measured in peripheral blood (preperfusion, then at 5, 30, and 55 min during perfusion, and finally at 5 and 60 min and 6 and 24 h after perfusion) and in recirculating perfusate (5, 30, and 55 min). While markedly elevated MMC concentrations (maximum 6290 ng/mL) were found in the liver perfusate, systemic concentrations remained low (maximum 45 ng/mL), indicating no considerable leakage. MMC concentrations in the perfusate constantly decreased during perfusion. After rinsing with 1500 mL saline, a mean concentration of 52.5+/-33 ng MMC/mL was measured in the washout from 5 patients. In 1 patient with a colorectal carcinoma, MMC concentrations in the perfusion medium were 10-fold and in the plasma 2-fold higher than in the other patients. This high MMC concentration caused severe intrahepatic vascular damage and finally led to the patient's death. In conclusion, IHLP and intrahepatic perfusion with MMC resulted in a high response of hepatic tumors. Systemic exposure of MMC can be reduced effectively by isolated perfusion. However, hepatic toxicity of MMC must be considered.