The main purpose of this study is to find out if screening for breast cancer with tomosynthesis mammography (3D) is better than with digital mammography (2D). The study will compare the two technologies and their ability to reduce advanced breast cancer in the screened population. This study will also compare the number of other/additional tests recommended after each mammogram.

Participants will be randomized (put into a group by chance) into the 2D or 3D group. They will be asked to participate in the study for 8 years. During the first 5 years, they will be contacted every year or every two years by the site to schedule and have their mammogram, either a 2D or 3D mammogram according to their study group. During the last 3 years, over the follow‐up period, their breast imaging records will be reviewed every year.