Karolinska Interventional Study of Mammograhic Density (Karisma-1)

The investigators want to conduct a feasibility study including 42 women who will be randomised to either 10 or 20 mg of daily oral tamoxifen. The primary aim of the study is to identify the time to mammographic density change and piloting the procedures. It is known that a density change is seen after 12 months of 20 mg of daily tamoxifen, but the clinical experience indicates that an effect of drugs influencing mammographic density could be seen already after a few months. The second aim of the pilot study is to see if there is a density change from 10 mg of tamoxifen equivalent to 20 mg and if there is a difference in adverse reactions between the two doses. Interim analysis will be performed at 6 months, monitoring both safety and level of mammographic density change.