As Brian says - check the NCCN guidelines here: http://oralcancerfoundation.org/treatment/pdf/head-and-neck.pdf

In the NCCN protocols (and there are others) definitive RT (radiation with no chemo) is ONLY listed as the one of the standards of care if the staging is T1N1 or T1N0. Print out the pages on staging as well as treatment and bring them with you to the appoinment.

If the radiation did not get everything (and they will check carefully for this in the coming weeks, both with palpation and a CT/PET scan at some point), they may elect for a neck dissection. If you look at the guildelines, you will see the various decision points. Scary looking at them, but maybe scarier not. PM and I can point you to some additional information.