A chap a few weeks ahead of me had to be, because his flow rate dwindled down to nothing.
He was supposed to be doing 23 sessions external beam and then having HDR brachytherapy, but his prostate had swelled and they couldn't get the bladder irrigation catheter in on the operating table, so he had to go back and finish his treatment as all external beam. Part way through that, he had to be catheterised so he could pee at all. It did have the advantage he didn't have to strain hold in the pee - he just closed a tap on the catheter.