Hi Pauline,
I had breast cancer in 2004 with a lumpectomy and radiation. I too was on tamoxifen for 5 years. In 2013 after 9 years and about to go out yearly checks my surgeon wasn't happy with my mammogram and ultrasound and ordered a core biopsy which turned out to be invasion cancer again in the same breast. I had a mastectomy and 6 months of chemotherapy. I'm now on Femera for the next 10 years. I'm negative for the BRCA gene but cousins are positive . My dad had breast cancer inially and in our family there are 16 people with it , some no love with us. One of my cousins had a double mastectomy aged 28 and died from breast cancer aged 44. There's no certainty and it doesn't follow any rules . Hope you have a positive outcome . Look at the websites and research . Wishing you well xx Bep