Kimberly,
They won't necessarily do radiation if all the nodes are negative, but they might, depending on the nature of the tumor. My nodes all came up negative but the head and neck tumor group at my hospital pushed strongly for radiation because of the indications that the cancer cells could be moving fairly aggressively. I can't second guess them at this stage since I've gone 15 years without a recurrence.
Mark is right -- if your friend's husband needs radiation, eating will be even more of a challenge. I never thought it would be hard for me to force myself to eat, but radiation taught me otherwise. As the others have said, when you get to that point, your blender is your #1 appliance. It's important during that process to stay in touch with the hospital nutritionist who will help monitor his weight and suggest ways to get additional calories. (And if he does have to have radiation, it alters the taste buds, so he might actually decide that tofu and wheat germ don't taste any worse than anything else! Easy for me to say -- I eat both of them.)
Cathy