R,
Most everyone here deals with the thought/fear of recurrence no matter what course of treatment we've had. I knew going in to my chemo radiation treatment that it was a one time shot. My attitude was to do everything I could now so there wouldn't be a recurrence later. I can't control if my cancer recurs or not. I pray that it doesn't and try to stay as positive as I can, but we all have dark days.
You are at one of the best facilties in the nation, have faith in your Drs and the treatment. Focus on making it through the treatment one day at a time. The future will bring what it brings.