Do you routinely hold immunotherapy during whole brain radiation?  

I don't routinely withhold immunotherapy during whole brain radiotherapy but would look at all aspects of the case including performance status, labs, goals of care, etc.. Alternatively with SRS I don't routinely withhold immunotherapy as well.

It is not really possible to hold immunotherapy agents during radiotherapy. The half-life of nivolumab is 28 days, ipilimumab is 15 days, pembrolizumab is 26 days, and durvalumab is 17 days, etc. Five to seven half-lives is typically a good benchmark to make sure the medication is out of your system...