Would you give lung SBRT to a patient with bullous pemphigoid on the chest and torso?

If this patient has a clinically relevant lung cancer (which, by the clinical description, it sounds like it is felt they do) then I would feel comfortable treating them with SBRT. The very focal nature of SBRT makes this a very different scenario than large-field radiation.

There is minimal data ov...

I have treated a couple of these patients over the past 20 years. I have not had an issue with toxicity. Simply have a conversation with the patient about the known unknowns and proceed with caution.