Hi Shelley and welcome to the forum. Because of the nature of cancer in general, he will be be monitored rather closely for the next several years. This is pretty much standard procedure no matter what kind of cancer he had. The answer to both your questions is yes - It might come back and the cells might still be there, hence the constant monitoring, AKA "watchful waiting". The first exams, scans and visits can be a little unnerving but this will pass in time. The biggest risk of recurrence is during the first year. 80% of recurrences (if they are going to happen) happen then. The followup visits will mirror the risk a bit. His risk will be even less since they caught it in an early stage. Needless to say, being cancer free the first year is a pretty good milestone to reach.

Yes radiation was very brutal - many say much worse than surgery. I was pretty much disabled for a year and I was in very good shape going into it.