Our last two Syrians lived to 2 years 8 months approx. They succumbed to the usual organ failure that can occur with age. Both became bloated with fluid latterly - which can be anything from heart or kidney failure to side effects of an unknown internal tumour. I also don’t think care is the main factor (although obviously bad care won’t help). I did wonder if diet made a difference. Our first Syrian had a standard hamster mix - Harry Hamster- which is mainly soya for protein. He was a pet shop hamster. Our second Syrian was a pedigree and had a soya free organic diet from the start. Made no difference to length of life. They were both healthy throughout and only had issues after age two and a half. Some Syrians do live until age three or over with nothing more than a bit of arthritis. So as with humans it is all unknown really
. I do think stress can make a difference to longer term health, and I have heard of a long lived hamster who had always been able to free roam. But ultimately they have a lifespan like humans.