I had a high dose of external beam radiation — SBRT, specifically — and have radiation cystitis (bladder) and proctitis (rectum) that seem to be permanent.

I've also noticed that the sensations tend to ebb and flow, even though the damage is constant. Different foods, UTIs, dehydration, or even just stress can exacerbate one or both of them.

But also, I've gotten used to them (the radiation was May–June 2022), and wouldn't count them among the biggest challenges from cancer and cancer treatments.