If it's cancer, she's good as dead right?
Not really, depends on lots of factors, mine had a mast cell tumor (cancer) cut out of her 5 years ago and has done just fine until last month when a complete and unrelated soft tissue tumor showed up, got that one cut out and hoping or the best but also realize she is 10 years old.
If it grew that fast it's an abscess. I think tumors would take longer to go from grape sized to grapefruit sized.
Unfortunately some cancer tumors can grow that rapidly, I would almost suspect cancer in this case, but maybe it is just because 2/3 bumps on my dog have been cancer