Proposal of the radicality grading as a criterion for therapeutic effectiveness of RFA against hepatocellular carcinoma, in relation to the local recurrence rate

PURPOSE: We classified the radicality of Radio Frequency Ablation (RFA) according to the extent of ablated area around the nodules, and measured the local recurrence rate for each radicality grade to examine its significance as a criterion for assessing the therapeutic effectiveness of RFA. METHOD: 99 nodules of 77 patients treated by Real-time Virtual Sonography-guided RFA were studied. We classified the radicality of the procedure into 4 grades (R grades: R0, R1, R2, and R3) according to the extent and pattern of the ablated area around the nodule, calculated the post-RFA cumulative local recurrence rate for each R number group, and analyzed the factors contributing to local recurrence. The distance of the site of recurrence from the treated nodule was also studied in the cases that showed recurrence. RESULTS: The cumulative local recurrence rate in 2 years was 3.7%, 13.6%, 52.6%, and 66.7% respectively for the R3, R2, R1, and R0 groups. Multivariate analysis showed that the R grade was the only significant independent factor contributing to local recurrence. Of the 25 cases of local recurrence, 20 had recurrence in the part where the ablative margin around the treated nodule was less than 5 mm. CONCLUSION: An ablative margin visible all around the treated nodule, preferably 5 mm or wider at all points, is a criterion for predicting good therapeutic effect of RFA.