Data processing
tumor
TUMOR, COMPLICATIONS
Continuous variables were transformed into categorical variables according to proper cutoff values. Age was cut at 65 years old to determine whether the patients belonged to the elderly. The cutoff value was set at 3.5 cm for tumor size as a tumor with a diameter larger than 3.5 cm has a high probability of failing to be completely ablated, thus two antennae were used. We chose 70 W and 10 min to cut off the ablation power and time respectively because ablation  ≥ 70 W or 10 min can lead to more ablation-related complications. Three missing values have been filled up by single imputation. If there were more than 10% of values were missing, this variable would be excluded from data analysis.To build the model and conduct the validation, data collected from the hospitals located in Jinan City (Shandong Provincial Hospital; Shandong Academy of Medical Sciences; Jinan Military Region General Hospital) was made as the training data set, while the data from hospitals located in other cities was made as the external validation data set, which is completely distinct from the training data.