Combination of radiofrequency ablation and transcatheter arterial chemoembolization to treat hepatocellular carcinoma: measurement of distance from needle tip to nodule for assessment of local tumor progression

OBJECTIVE: This study was performed to determine the relationship between the minimum distance from the radiofrequency ablation (RFA) needle tip to the tumor and local tumor progression (LTP) of hepatocellular carcinoma (HCC) nodules and identify prognostic factors for LTP. METHODS: We reviewed 197 patients (197 nodules) who underwent RFA after transcatheter arterial chemoembolization for HCC from January 2010 to January 2015. Three-dimensional registration of images was used to calculate the minimum distance from the tip to the tumor. We then divided the minimum distance into two groups: <2 and ≥2 mm. Contrast-enhanced computed tomography was performed after treatment. The LTP rate was calculated 1 and 3 years after RFA. We performed multivariate analysis to identify independent prognostic factors for LTP. RESULTS: The cumulative 1-year LTP rates in the <2- and ≥2-mm groups were 82.7% and 4.3%, respectively, and the cumulative 3-year LTP rates in the two groups were 94.8% and 10.8%, respectively. The minimum distance from the needle tip to the tumor was an independent prognostic factor for LTP. CONCLUSIONS: A minimum distance of 2 mm from the needle tip to the tumor should be completely ablated along with the tumor.