Hello, I am saddened to read of your Fathers diagnosis.
The proposed treatment plan of concurrent Chemo and radiotherapy sounds like the normal plan for this cancer.
I am presuming that he has had the tumour removed and has also undergone a neck dissection. Perinodal extension tells me that cancer cells have escaped into surrounding tissue and he will need radiotherapy to deal with this.
It is my understanding that immunotherapy is usually used in metastatic Head and Neck cancers that have previously been treated with Cisplatin chemo..
Are you able to get a second opinion on treatment options from a top cancer centre? I would advise that, although I think the proposed treatment is correct according to current standards.
I'm sure someone with more knowledge than I have will come along shortly to advise you further.
Take care,
Tammy

Caregiver/advocate to Husband Kris age 59@ diagnosis
DX Dec '10 SCC BOT T4aN2bM0 HPV+ve.Cisplatin x3 35 IMRT.
PET 6/11 clear.
R) level 2-4 neck dissection 8/1/11 to remove residual node - necrotic with NED
Feb '12 Ca back.. 3/8/12 total glossectomy/laryngectomy/bilat neck dissection/partial pharyngectomy etc. clear margins. All nodes negative for disease. PEG in.
March 2017 - 5 years disease free. Woohoo!