Althea

hi no one can really answer that question for you, not even the doctors
a lot will have to do with the kind of cancer it is- both of my parents were CURED of an early stage squamous cancer that had not yet spread
(they both got a second kind of cancer though, my mom is now on her second lung cancer and it is terminal, my dad died of carcinoid cancer)

i understand the uncertainty is rough and stressful, but unfortunately nothing in life is certain, so it does you know good to stress over it. hell anyone of use could be hit by a bus tomorrow, we never know
try to focus on living each day the way you want to, spend as much time with your mom as you can, and cherish the time you do have
if your mom has to have lung surgery she is going to need your support, it is a very very difficult surgery so try to prepare yourself for that, without frightening her any more than she probably already is.
it will be hard for her to sit up and move around, and yet at a certain point the doctors will be telling her to try to do more, to try to breath deeper, and all of this will be painful and frightening for her. Be prepared for a huge ugly scar with large staples in it, and a fairly large ugly drain coming out of her chest.
i am not trying to scare you, i just think you will feel better if you know what to expect
keep in mind that he physical health before she has the surgery plays a part in her recovery- generally speaking, the better shape she is in now, the easier the surgery will go.
but that is just in general, every case is unique, which is why it is hard to say what will happen with your mom
as far as i knew no one survived more than 2 or 3 years after lung cancer surgery, then i met a woman who had had an entire lung removed 17 years before! and she was doing fine
so never give up hope
i think you will see that the stress of not knowing is easier to bear than the loss of your mom being a certainty any time soon

good luck