My mother is a breast cancer survivor and my mother in law is currently fighting the disease so I completely understand where you are coming from. It's a silent killer and that's why awareness and screenings are so very important.
Yes it definitely is. For my mother and grandmother both they had yearly mamograms and apparently developed the disease between mamograms. By the time they had caught it on both of them it had already spread to lymph nodes. It was very aggressive. I am glad that your mother survived it and hope that your mother in law does as well!