Rawnoc---One study only----"RF ablation is increasingly used as minimally invasive therapy for treating liver tumors, both primary hepatocellular tumors and hepatic metastases ( 2 ). RF ablation is highly effective for tumors less than 3 cm in diameter but is less effective for large tumors. Multiple RF electrodes are typically required to treat large tumors. In one study ( 3 ) of 121 tumors between 3 and 7 cm in diameter, 536 ablations were performed and the local recurrence rate was 24%. For even larger tumors, the recurrence rate will likely be much higher."