to 0.109 (± 0.005) for CD4 + and 0.11 (± 0.012) for CD8 + T cells against HCC, and to 0.115 (± 0.031) for CD4 + and 0.15 (± 0.02) for CD8 + cells for colorectal metastases (P < 0.0001). No increased SI was observed with nonmalignant tumor tissue at all time points. Before RFA cytolytic activity against the respective cancer cells was low with 2.62 (± 0.37) relative luminescence units (RLU), but rose more than 100 fold 4 and 8 wk after RFA. Spontaneous release was < 2% of maximum release in all experiments. CONCLUSION:Patients with primary and secondary tumors of the liver show a significant tumor-specific cytotoxic T-cell stimulation with a dramatically increased tumor specific cytolytic activity of CD8 + T cells after RFA. INTRODUCTIONOpen surgery is still the gold standard for the treatment of hepatocellular carcinoma (HCC) and liver metastases of colorectal cancer. However, more than 75% of these patients are non-resectable for various reasons, such as size and location of the tumor. Radio-frequency thermal ablation (RFA) is a common therapy option for unresectable liver tumors. Thus it was shown that RFA and laserinduced thermo-therapy (LiTT) can achieve survival times comparable to surgery in selected patients [1][2][3] . RFA uses a radio-frequency current to induce coagulation necrosis which results in a local thermal necrosis accompanied by Activation and dramatically increased cytolytic activity of tumor specific T lymphocytes after radio-frequency ablation in patients with hepatocellular carcinoma and colorectal liver metastases www

Contrast-enhanced sonography is highly efficient for the detection of tumour vascularity in HCCs. The majority of HCCs--regardless of histological differentiation--can be characterised as hypervascular lesions in the early arterial and arterial phase with irregular tumour vessels using contrast-enhanced sonography. In addition to B-scan sonomorphology, contrast-enhanced sonography may offer helpful information in patients with liver cirrhosis and focal liver lesions.

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.

The aim of this animal experiment was to investigate the cellular and vascular reactions in the liver of juvenile domestic pigs produced by a radio-frequency thermoablation (RFTA) applicator perfused with saline solution. Methods: A total of 13 coagulation necroses were produced in the liver of 3 anesthetized domestic pigs using RFTA. The pigs were dissected and the coagulations examined. Results: The mean macroscopical length and width of the coagulation zones with a hemorrhagic marginal zone after a 5-minute application time were 34.1 ± 8 mm (22–46 mm) and 20.8 ± 4 mm (12 ± 28 mm) respectively. The sonographically determined diameters correlated significantly (r_length = 0.741 and r_width = 0.923). Three areas in the coagulation zones could be histologically distinguished: (1) central necrosis zone, (2) hemorrhagic marginal zone, (3) sublethal damage zone. Large vessels did not show any substantial changes after RFTA. Venous vessels less than 1 mm were completely thermally denatured or destroyed. Conclusions: Tumors in close proximity to large blood vessels can be treated by RFTA with ‘wet electrodes’.

RF ablation of liver tumors with perfused needle applicators prolongs survival in the VX2 rabbit liver tumor model, regardless of whether complete remission is achieved. In comparison with controls, RF ablation results in a lower frequency of metastases.