This is a very difficult situation for you to be in.
If this was my 90 year old Dad I would not be seeking all the bells and whistles of treatment. It is difficult enough for a 60 year old. Let alone a man of 90 who also has cardiac complications.. I would maybe look to have the tumour debulked as this would contribute to comfort and then talk to Hospice.
Be guided by your gut feelings and what your Father would like to do. Also taking into consideration the medical teams advice.
In my experience in the NZ hospital system only palliative care would be offered here. It is all about the benefit and quality of life your Father is likely to have.
Thinking of you,
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!