I was a total coffee fiend. Fresh ground & filtered through a caffetiere, strong and without milk or sugar. Nothing was going to get between me and my coffee fix. I planned things before my chemo & radio started and aimed to drink 2-2.5 litres of non caffeinated fluids a day, not including the coffee which I continued to drink every morning up to the treatment beginning.
I had my first chemo & radio on the Monday, then daily radiotherapy. On Wednesday I thought my regular morning coffee fix tasted and smelled odd, on Thursday I threw the whole lot up. I couldnt bear the taste or smell of the stuff for the rest of my treatment nor for about six weeks after it ended. Three and a half months later I can just about tolerate a small coffee occasionally, but I've at last started to like the smell of it again!
Everyone is different, you might continue to love your coffee and when going through this treatment you should hold on to those treats in the midst of it all. Just in moderation. The main thing is to look after your kidneys & bladder. Get into the habit of flushing them through every day by drinking to reduce the risk of urine infection & irritation. Caffeine (and alcohol) irritates the bladder and also works as a diuretic which stimulates the kidneys to fill the bladder more quickly. So maybe have a glass of water around the same time so that you can dilute that effect?
Pelvic radiotherapy also risks exposing your bladder to some of the treatment effect because it is so close to your cervix, so it benefits from all the help you can give it. It's as important to think about this in terms of reducing the late effects of pelvic radiation, not just the acute ones that might happen during treatment. My team specifically asked for me to have a full bladder for every radiotherapy treatment, because it helps to push other bits of bowel out of the way and assists with treatment targeting accuracy. Doing this helped me keep my daily fluid intake up, made me work hard to use & control my bladder muscles (!) and helped me feel as if I was doing something kind to my kidneys which were dealing with flushing out chemo & endless amounts of steroids, painkillers, anti-emetics etc...