Radiofrequency Ablation Of Liver Tissue Adjacent To Intrahepatic Large Bile Ducts: A Safety Study

1. BackgroundSurgery is the most effective therapy of liver cancer. However, due to the size, location, and number of tumors as well as liver function, less than 30% of primary hepatic carcinomas and 10%-20% of secondary hepatic carcinomas are indicated for surgery [1, 2]. At present, liver malignant tumors are subjected to comprehensive therapy, and comprehensive therapy dominated by local treatment is used for unresectable liver cancer [3, 4]. Local treatment of liver cancer includes trans-hepatic artery or trans-portal vein embolism and interstitial ablation such as anhydrous alcohol injection, freezing, exposure to microwave, laser, high-intensity ultrasound and radiofrequency ablation (RFA). Because local therapy of liver cancer is widely indicated and leads to minor injury but marked short-term therapeutic effect, it has been widely used to treat liver cancer. RFA therapy for liver cancer has become an interstitial ablation method that is used the most widely and develops the most quickly [5,6 ] .Radiofrequency ablation technique has been used to treat liver tumor since the early 1990s, and the principle involved is that high temperature (> 42°C) may treat tumor. During RFA treatment, a radiofrequency needle electrode is inserted into the site of interest, which leads to local high temperature up to 90-110°C. It has been shown that high temperature may directly cause coagulation necrosis of tumor cells, and if temperature is not high enough to cause necrosis, another pattern of cell necrosis, i.e., apoptosis may occur. Moreover, tumor tissue inactivated under high temperature may act as tumor vaccine as a result of altered cell immunophenotype, thus further triggering the antitumor immunity and exerting special antitumor effect. In addition, blood vessels in tumor are circuitous and irregular, with slow blood flow within, and are lack of innervation; therefore, after heating of liver tumor, heat loses slowly, and temperature rises more quickly in the tumor than in normal tissues. Meanwhile, intracellular acidic metabolites exhibit stronger lethal effect on...