Temperature distribution along the symmetry axis r = 0 for cases 1 to 4. Both temperature dependent and constant conductivity was used for the only fat models and the tumour models. The electrode tip was located at Z = 0.09. Temperature dependent conductivity creates significantly bigger thermal lesions. Additionally, the tumour increases the temperature in the tumour compared to the models with only fat. The 50°C margin is increased 4.7 mm in the tumour direction for both temperature dependent and constant conductivity when the tumour is incorporated, i.e. the difference in thermal lesion size between the tumour and non-tumour models is not affected by the used conductivity type.