Introduction. Local tumour progression remains the main problem after radiofrequency ablation of liver tumours and is usually the only factor of treatment efficacy. The aim of our study was to assess factors predicting local tumour progression after radiofrequency ablation of malignant hepatic tumours that could be evaluated before intervention.

Materials and methods. We have studied 68 malignant primary and metastatic hepatic tumours treated by radiofrequency ablation. Ablation was performed using perfusion electrodes. Evaluation of tumours before ablation and during the follow-up was performed by means of contrast enhanced computed tomography and ultrasonography. Tumour type, size, echogenicity, density, enhancement pattern and proximity to large hepatic vessels closer than 5 mm were analysed as risk factors for local tumour progression. Local tumour progression was assessed by follow-up CT scans and ultrasonography. The Nelson–Aalen cumulative risk estimation method and log rank test were used for statistical analysis.

Results: 58 successfully treated hepatic tumours were suitable for the final analysis. The local progression of nine (15.5%) tumours was detected in the follow-up. The mean follow-up time for the tumours was 16.3 months, range 1.7 to 38.7 months. The size of the tumour more than 30 mm in diameter and its proximity closer than 5 mm to large hepatic vessels were identified as risk factors for local tumour progression after radiofrequency ablation. Tumour type, echogenicity, density and enhancement pattern had no significant influence.

Conclusions. The size of the tumour and its proximity to hepatic vessels closer than 5 mm should be taken into consideration when performing radiofrequency ablation of liver tumours and during the follow-up.

Keywords: radiofrequency ablation, hepatic tumours, local tumour progression, risk factors