Guys, need some advise...
My granddad aged 76 was diagnosed with oral cancer in the lower lip in november 2010. We opted for surgery and Dr. removed the cancer along with nearby tissues and sent the same for biopsy.
Biopsy was clear as in there was no cancer in the surrounding tissues.

Last year again in october we noticed a small red lump in his lower jaw towards the extreme right. The Dr. 1st thought it was an ulcer and mostly benign and prescribed some ointments.
Since it didnt go for a month we went in for a biopsy which classified it as SCC. It re-occured.
We went in for a surgery and got it removed along with surrounding tissues.
The biopsy came out stating that the margins were not clear, hence there were still cancer cells in his mouth.
We were suggested to go in for 30 cycles of radiation under rapid arc technology.
We went through the first 15 with relative ease, but the next 5 were not good at all as, his skin exposed to radiation burned out, he had ulcers all through his mouth which looked like they would bleed, his BP started fluctuating because of insufficient salt intake. And he is almost in a depression. He also had urine infection during 10 & 15th day of his cycle and was administered anti-biotics.
PS: His PET CT before the radiation could not detect any cancer cells.

Now we are of the opinion that it is better to discontinue the treatment as we assume the microscopic cancer cells would have died by now. We are unable to take a call as the Dr. here says he want to finish the treatment and the other Dr. Says that its ok if we quit.

We know that we can push him and all of us can work through these last 10 cycles, but we are unable to take a call as he is in real bad shape and even if he sips water his mouth goes on fire.

Kindly advise.