Hi Jane,
After my tumor was removed, I received radiation although my lymph nodes were clear. Becuase there was no tumor to target, I was not a candidate for IMRT radiaton (the type that spares a lot of adjacent tissues). Rather the goal was to radiate those areas of the head and neck where any lingering cancer cells would likely be located. This included the tumor bed, the lymph nodes, muscle tissue, etc. with a broad radiation field. I have dry mouth now, but the saliva flow is slowly improving as is my sense of taste.
You might find it helpful to do a search on the OCF website for occult or micro metastasis. If I remember the statistics correctly, in almost 30% of cases where surgery has removed the tumor and there is no sign of spread to the lymph nodes, recurrences occur. I would be inclined to follow your doctor's advice.
While radiation is an extremely unpleasant experience, most of the acute symptoms (the pain, discomfort, mucous, etc.,) are temporary and the benfits may be life saving. As Cathy mentioned, post-radiation, dental care and hygiene is extremely important.
Best wishes with this difficult decision. Sheldon