A new study could determine if 3-D mammography reduces a woman’s risk of developing life-threatening breast cancer more than 2-D.

The ECOG-ACRIN Cancer Research Group (ECOG-ACRIN) and the National Cancer Institute (NCI) have developed the Tomosynthesis Mammographic Imaging Screening Trial (TMIST) to compare the two types of digital mammography in breast cancer screenings. ECOG-ACRIN will lead the study.

“The information related to detecting life-threatening cancers is important because it gets to the purpose and essence of cancer screening,” Dr. Worta McCaskill-Stevens, M.D., M.S., chief of the Community Oncology and Prevention Trials Research Group at NCI, told HCB News. ”Another important aspect is that TMIST will compare the benefits and harms between 2-D and 3-D.”

3-D mammography is likely to detect more findings that require follow-ups and lead to more procedures and treatments than 2-D. It is unknown whether 3-D is better able to reduce a woman’s risk of developing an advanced, life-threatening form of cancer.

The trial will follow 165,000 women between 45 and 74 who are planning to undergo routine mammograms. Researchers will use the findings to determine the best course of action for screening women, as well as how to help women make informed decisions regarding screenings.

Participants will each be assigned to undergo either 3-D or 2-D mammogram screenings. Most will be screened annually. Postmenopausal women who show no high risk factors will be screened every two years. The study will also take into account diversity, basing participants on geographic location sites, race and ethnicity.

Data from each mammogram will be collected and evaluated, including imaging that shows no signs, suspicion or diagnosis of breast cancer. Follow-ups for imaging and biopsies will be reported. All participants will be checked for breast cancer status, treatment and outcomes from the time each starts the trial through at least 2025. Women who are diagnosed with breast cancer during any part of the study will continue to be a part of it and receive treatment.

All participants are encouraged to voluntarily submit blood samples and a swab of buccal cells from inside the mouth as part of TMIST’s effort to create a biorepository for future genetic markers for breast cancer. This will enable doctors and women to determine the best methods for screenings and evaluate risk factors of individual patients for developing diseases.

Tissue will also be collected from women who undergo biopsies as part of follow-ups for mammogram findings, allowing TMIST researchers to study the biology of screen-detected abnormalities and to evaluate the overdiagnosis of breast cancer from screenings.

“It is a trial that will enable us to gain knowledge about how to move beyond our current ‘one size fits all’ approach, where we screen women the same way, based on age-specific guidelines, to more personalized strategies that tailor screening to each woman’s own genetics and individual breast cancer risk factors,” Dr. Etta D. Pisano, the study chair and a professor in residence of radiology at Beth Israel Deaconess Medical Center and Harvard Medical School told HCB News. “In addition to finding out what technology works best, TMIST is about learning how to help individual women get what they need to avoid death from breast cancer.”

The study is now open for enrollment at several mammography clinics in the U.S., with more planning to begin enrollment over the next several months. About 100 U.S. clinics in total plan to participate in the trial, along with a few locations in Canada where the findings from a smaller lead-in study of 3,000 women are being used to inform TMIST.

Women will be informed about enrolling in the trial when it is time to schedule their next routine mammogram.