i have been told that i have micros in my left breast. changes from last year. i am 48, have no history of bc in my family. i do not smoke, do not take the pill and do not take hormones. i am healthy in the regard that i am not taking any meds for chronic medical conditions. i do take vitamns at times. my question is how concerned should i be that this is cancer? i have a biopsy sceduled but not for a week. also, how quickly do these spread and are they considered pre cancerous because they have not formed a lump or mass yet? if they are cancer, is that what they do?