No one in my family had cancer until they were in their 70s. I did not test positive either. When I was 40 I had a ductile lavage after lumpectomy. They felt that I had 7 to 8 years of being clear. At that time they said I was 2 stages away from cancer. It was up to me take the Tamoxifen. I did not. 8 years later it was found on a MRI, 3 months after a mammogram at Stage 0. MRI Had caught it very early. I took Tamoxifen for 4 1/2 years until I had a black blood clot.