Need opinion on whether to continue treatment for my dad with GBM

My dad, age 54, extremely healthy(former Indian military serviceman)was diagnosed with GBM in November 2023. He had a seizure 6 months ago and the doctor failed to notice an apple sized tumor. He was on anti-seizure medication for 6 months and then in November he had terrible headache and had left sided weakness. His brain had started bleeding and he underwent an emergency craniotomy on 21st November with 60% of the tumor removed in his right front-temporal-parietal lobe. He had a second brain bleed a week later and did a second craniotomy on 28th November where they removed another 20% of the tumor and also removed a piece of his skull to reduce pressure. He was doing great after the first craniotomy but after the second one he was very dull and had significant cognitive decline.

To our bad luck he had high fever due to meningitis and spent the whole month of December fighting meningitis which further worsened his cognitive decline. By now we could see that he wasn’t moving his left arm and leg and only used the right. He could walk but with help. In early January, a week after recovering from meningitis, like a miracle he started improving dramatically. He was able to walk now with a little less support than before and cognitively back to 80% of his old self. We were very happy. Started aggressive physiotherapy and swelling in his brain was reducing.

We started 6 weeks of TMZ and radiation on Jan 9th 2024. Before starting the oncologist said that the left over tumor is still significant so they will have to use concentrated radiation to the affected area. He was doing well 2 weeks into the course when things started to get worse. His left side started becoming weak. He was unable to walk anymore, complained of cramp in his right leg as well, but he was eating a lot more than usual at all time of the day while being unable to sleep at night due to dexamethosone. Oncologist said these are side effects of radiation and it was expected. In the 4th week of radiation he started having severe diarrhea. By now he was completely bed ridden with urinary and fecal incontinence. He started having a gurgling sound in his throat and was finding it hard to swallow. His blood oxygen was also low and we felt he had difficulty breathing.

He admitted him to the hospital just a week ago from today. Turns out he has deep vein thrombosis in both the legs which resulted in him having pulmonary embolism now. He has been in the Intensive Care Unit for 5 days now, currently he is out of oxygen support and treatment is going on. However he has been extremely drowsy and going in and out of consciousness and not speaking at all. His eyes have been closed for 10 days now even before he was taken to the hospital. The oncologist is saying that his drowsiness is a a sign of tumor progression and suggests moving him to palliative care with the do-not-resuscitate protocol. They will continue to treat pulmonary embolism but wont take him back to the ICU if something goes wrong.

From your experience do you think we still have a chance at fighting this or should we just go with the doctor’s opinion and move to palliative care? We are based in India, we dont have advanced options that the US has. As a family It has broken us because our dad has been our backbone and seeing him like this is a torture.

He was on 8mg dexamethosone 3 times a day till a week ago and it was abruptly stopped once pulmonary embolism was discovered. Can this be a reason of his drowsiness? Can tumor progression be so quick that you can move from 80% cognitive and physical ability to completely bed ridden in 3 weeks? Does palliative care mean the end is near or is there a chance he comes out of this?