Welcome, and sorry to hear of your father's recurrrnce, which is not uncommon. As Cheryl mentioned, surgery is the first, and best option for recurrences, with or without radiation or chemoradiation. I had 8 recurrences, several which were treated by surgery alone due to my health condition from chemo. Later on I did surgery with Chemoradiation, and will again any week now, so there is hope for recurrences, and do see a CCC who often deal with these cases.
Good luck.