Dizziness when to see a ENT?

I just came across this research article. Upfront Radiosurgery vs Wait and Scan in Vestibular Schwannoma1

Interesting article. Reading carefully and you find that while upfront radiosurgery does have a preventive effect on tumor growth, all of the secondary measures (hearing, balance, etc.) have similar results at five years among the treated and control groups. I’m wondering what happens after ten or even twenty years. Perhaps the study didn’t run long enough to see a difference in secondary measures. I was hoping for something more definite.