We asked about the 'terminal' classification at the hospital. Tony's (advanced) cancer is not cureable but is not going to kill him for - hopefully - several years yet. It's largely a matter of semantics, but you do need to have an answed when, say, a travel insurer asks whether you have received a terminal prognosis. Both the oncologist and the nurse said, no, this was not the case yet. He is not 'end-stage' and is very treatable. I think terminal is more apt when you know you have only months to live and no further treatment will help.
I really don't know whether that's how an insurance company interprets it; all we can do is anwer questions honestly, and explain that there are no clear answers to some of them. That's how we're taking it for now, anyway. I'd be interested to hear if anyone else has further thoughts on this.