I'm so sorry to hear about your grandmother. I don't think you should worry about steering her wrong. Whatever she wants to do is the right choice. I hate to say it, but there probably aren't any really good choices.

If your grandmother is interested in aggressive treatment, it might be a good idea to get a second opinion to see if they agree about the sequence of surgery and chemo/radiation.

It might be good to ask the doctor how long s/he would expect it to take to metastasize. I'm not a doctor, but I would guess less than a year, based on what I have read. If the cancer spreads, at some point she can enter palliative care/ hospice, where they will do their best to maximize quality of life.