Hi Sharon, I also had breast cancer that didn't show up in a mammogram. A small cyst showed up with the ultrasound, and no one seemed at all concerned. Fortunately I had a radiologist with a keen interest in breast cancer checking my ultrasound, and whilst he was sure it was a harmless cyst, decided to do a biopsy. This showed a very aggressive invasive cancer. I'm so glad I listened to my gut feeling, because even though I had a normal mammogram only 3 months before, there was something sinister there that no one could feel or see. My GP is wonderful, and would always follow up a worry with a test. I am forever grateful. Good luck with everything. Love Chris xx