@dhueter Hello and welcome.
I hope your friend has the removed tissue biopsied each time. A consult with an oncologist wouldn’t be out of the question as well.
Going to the same ENT and getting the same results is maintenance. Finding a reason and addressing this is science. We always need to take our healthcare into our own hands if/when our current medical help fails us.
By reaching out, you have taken the first step. Your friend’s primary physician should give the referral needed if required.