Tomosynthesis Mammographic Imaging Screening Trial (TMIST) is a breast cancer screening trial that will compare two methods of mammography over several years to help women and their doctors decide the best ways to screen for breast cancer in the future.

The two screening methods being compared in TMIST are digital and tomosynthesis mammography.

TMIST will follow women who are already planning to get screened routinely for breast cancer, to share data from their screening tests, and other possible follow-up data, with researchers so that they may analyze the information.

In order to participate in the study the participant must be:

• 45-74 years of age
• Scheduled or intending to schedule a screening mammogram and The participant must not
• Be pregnant, intend to be pregnant, or lactating
• Have symptoms of breast disease
• Have had a screening mammogram in the last 11 months
• Have a history of breast cancer
• Currently have breast implants or other breast enhancements If the participant decides to participate, they will be involved in this research study for up to 8 years starting with the first mammogram. 

During this time:
• The participant will be randomized (assigned by a computer like a flip of a coin) to get either 3D or 2D mammograms for the first 5 years of the study, or the end of the research study, whichever comes first

Most women in the trial will be screened annually, but postmenopausal women with no high-risk factors will be screened every two years.

We will follow the participants' breast cancer status for at least 3 years and up to 8 years in total, including the screening years, by reviewing medical records and, if needed, contacting the participant by phone.