My grandma got a biopsy today, and we found out she could have the cancer cut out if it hasn't spread yet, but we're not sure whether or not it has. All I know is if it has spread, and she has no treatment (which she won't) then she ahs 6 months tops.

Is she otherwise healthy? Why doesn't she want treatment? If she's feeling unwell, has other health issues or maybe after talking to the dr feels that the surgery & treatment needed afterwards would be too much & so leave her without a reasonable quality of life then perhaps her decision is soundly based.

Talk to her about how you feel & ask her why she feels as she does, perhaps then you will both feel better, or perhaps you will just have to accept her decision, it is her life & her right to choose.