When is it safe for a rectal biopsy in a patient with prior prostate radiation?

A biopsy of rectal tissue that has been radiated will have a higher risk of developing non-healing wounds and ulcers. Part of the reason that biopsies are discouraged as well as radiation proctitis is a clinical diagnosis and that biopsies of proctitis are certainly not needed to confirm this. Recta...

No. You need a really good reason which would be unlikely.