My great grandmother is 90 years old. She had breast cancer 4 years ago and both her breast and lymph nodes from under her left arm were removed. She has been doing great up until about 2 weeks ago. She had a bone scan back in August of 06 and it was clear as a bell. She since had been suffering from fractures in her back. We had a bone scan done on her 2 weeks ago and it came back that she had metastatic disease all in her bones and in her skull. This is not in her brain right now. My question is, how fast does this spread?