Background and purpose: Radiofrequency ablation (RFA) is one of the effective treatment methods for primary liver cancer and metastatic liver cancer. The purpose of this study was to investigate the risk factors of residual tumor after RFA for hepatic malignancies. Methods: A total number of 302 hepatic malignancies cases with 691 tumors after ultrasound-guided RFA from Jan. 2010 to Mar. 2013 were retrospectively analyzed. Single factor and multi-factor Logistic regression model were used to analyze the risk factors of residual tumor after RFA. Results: Complete ablation cases were 90.07% (272/302) for patients and 91.46% (632/691) for tumors

and the ablation residual rate was 8.54%. Ablation residual rates for tumor ≤3 cm

3-5 cm and 5 cm in diameter were 6.30%

9.57% and 28.57%

for tumor close to the intrahepatic vascular and gallbladder were 17.14% and 18.52%

for with and without combination with other local treatments were 7.02% and 13.41%

respectively. Multivariate analysis showed that tumor size5 cm (P=0.044)

proximity to large vessel (P=0.039) and without combination with other local treatments (P=0.001) were independent risk factors for ablation residual. Multivariate analysis showed that tumor near the intrahepatic vascular (P=0.014)

single needle RFA (P=0.047) and without combination with other local treatments (P=0.023) were independent ablation residua risk factors for tumors between 3-5 cm in maximum diameter. Conclusion: Ultrasoundguided RFA can achieve satisfactory ablation effect. Tumor close to the intrahepatic vascular

tumor diameter 5 cm and without combination with other local treatment act as the independent risk factors for ablation residual. For tumors between 3-5 cm in diameter

in addition to close to intrahepatic blood vessels and without combination with other local treatment

single needle RFA is also another independent risk factor for ablation residual

and double-needle or multineedle treatment can improve the ablation efficiency and reduce residual rate.