What Is The Success Rate Of Tonsillectomy?

My daughter is having surgery to remove her tonsils on Wed. She only has one enlarged tonsil that has been enlarged for as long as we can remember. She hasn't been sick with it. In researching this, I keep reading about cancer being the cause. What is the percentage of people that only have one enlarged tonsil where everything turns out to be fine? Are there more cases than not, in this type of situation, does everything turn out to be okay?