Answer
As enegry transfer through microwaves beamed into a tumor cann't be considered as heat transfer as energy is not transfer due to temperature difference between system and surrounding.
Work Step by Step
When stored energy interacts with the system in such way that fulfils the definition of thermodynamic work is called work transfer i.e. "Work is done by a system on its surroundings if the sole effect on everything external to the system could have been the raising of a weight"
Energy is considered as heat transfer if it is induced only as a result of a temperature difference between the system and its surroundings.
