Not sure what causes HPV but I had the same and never smoked but second hand smoke can be a factor I’m sure and being a fire fighter exposure to all of those I’m sure contributed to his case .I had 35 radiation and 7 chemo same as he did Lost 90 lbs put in a feeding tube and went for 60 hyperbaric oxygen treatment 2 hrs a day 5 days a week for 60 days .It saved my voice box and created new blood vessels and blood supplies to radiation damaged areas and saved me back to eating full blast and put on 4o lbs .If you do anything please look into Hyperbaric you will be glad you did .Good Luck 🤞🥊