couple of days ago, one of my sisters found out she had small cancerous cells in her breast. She doesn't know everything yet, whether it's genetic or not, how developed it is. She had a mammogram back in November and everything was fine. FYI, she's 40 years old and has 3 kids. Perfectly healthy otherwise. This comes as a huge shock as no member of our family ever had cancer.
So my first question is: How bad is it? It's obviously an early stage, but it can't spread quite rapidly no?