Hello and sorry about your situation.
In the words of my senior oncologist, I had way too much cancer for any surgery and I needed to be hit as hard as I could with old school chemo and radiation because he had one chance to kill it or my prognosis would not be good.
With all that said I can only attest for radiation along with chemo.
One thing for certain is that you need a complete oral examination from an oral surgeon. Any teeth that are within the radiation impact area that may be at risk(crowns, filled, decay etc) must be extracted and 21 days of healing prior to any radiation. After radiation treatment you will need Hyperbaric Oxygen treatments for 30 days prior to a tooth extraction or filling and 30 days after…. I had my wisdom teeth and 3 molars extracted prior to radiation!
As far as radiation, everyone can respond differently so it’s hard to say how it will affect you. All we can say is what it did to us.
As for me, chronic migraine 24/7, tight neck, tight jaw, dry mouth, difficulty swallowing food and sometimes liquid, cough, hearing loss and tinnitus (most likely from Cisplatin), speech impairment, fluoride treatments/prescription toothpaste and more.

Wishing you the best,
MOJO