Hi, So sorry to hear all your partners history.
At this stage if they wont offer him further radiotherapy are they offering surgery?
My husband had total glossectomy/laryngectomy/pharyngectomy . Chemo alone will not have a curative intent. If I was you I would push hard for more surgery.
I'm sure others will chime in with more advice .
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!