Nina
Your question is a very good one. Unfortunately, there is no good answer. Numbers or percentages are what we all crave but even when there are generalities like recurrence or metastasis (fancy term for "spreading somewhere else"), we can't attach them to any individual.
That said, and remember I am not a doctor of medicine but law, I want to try and help [quote]I am so worried and confused and in desperate need to find some answers.[/quote]
My GUESS (based on Stage 1, the tumor board advising against radiation, cancer is one node out of 20) is that the likelihood is low. My understanding is that the lymph node system is a major gateway for the cancer spreading out of the oral cavity to "elsewhere". Think of the lymph nodes as "stepping stones" so if a lot of them have cancer, then it is clearly on the move. It does not sound like that here. Again no guarantees. Mine was Stage IV, had spread to several lymph nodes, and even came back after months of radiation and chemotherapy and it has NOT "spread to somewhere else in the body".
You need to be strong for your Mum, and worrying won't help either of you. So take a deep breath and try to relax. Just be sure to have your Mum examined on a very regular basis. Best wishes and good luck