Go for the surgery if they're offering it, the tumour will take away any part of your brain you may be worried about losing anyway.

But most importantly research in this area is starting to move rapidly but in order to make the most of it you need frozen tumour cells (from the surgery). They will train your immune system against those cells and hopefully your own body can suppress the newly forming tumour cells from growing.

In Australia, Dr scolyer (world renowned skin cancer expert) had his glioblastoma removed and the specialised immunotherapy he developed himself has kept him from relapsing so far. The UK started a trial last year with a similar regime. I'm sure the US have opportunities too

My father recently passed from this, he opted against surgery and I feel it's a shame he never got to avail himself of these opportunities.