For insurance, how do you justify medical necessity for IMRT to the pancreas in the preoperative, unresectable, and post-operative settings?

I work in prior auth.

In all three cases, IMRT would be auto-approved where I work.

Other third parties are restrictive about this and it is unclear to me why.

In any case, though it is burdensome, if I was in a region that was restrictive, I would do a comparison plan right off the bat. As annoying...