TMIST clinical trial comparing 2D and 3D mammography extends to United States

By Staff News Brief

The Tomosynthesis Mammographic Imaging Screening Trial (TMIST), the first randomized trial to compare two-dimensional (2D) conventional full field digital mammography (FFDM) with three-dimensional (3D) digital tomosynthesis (DT) for breast cancer screening, is now open for enrollment in the United States. The study was developed by the ECOG-ACRIN Cancer Research Group (ECOG-ACRIN) and the National Cancer Institute (NCI). ECOG-ACRIN is leading the phase three clinical trial (NCT03233191).

>Currently TMIST researchers in Illinois, Indiana, Louisiana, Nevada, and New York are enrolling healthy women ages 45 to 74 who are already planning to get routine mammograms. About 100 mammography clinics in the United States are planning to participate in the trial and are opening on a rolling basis over the next several months.

By taking part in TMIST, the 165,000 planned participants will provide critical information that will help researchers learn how to most effectively screen women for breast cancer and help women make informed decisions about the screening tests in the future. Women are being told about the opportunity to enroll in the trial when they schedule a routine mammogram. Once enrolled, they will be assigned to either 2D or 3D mammography screening. Most women enrolled in the trial will be screened annually. Postmenopausal women with no high-risk factors will be screened every two years.

“Nearly 50 million screening mammograms occur each year in the United States, yet it has been decades since a large-scale randomized trial of mammography has been done,” said Worta McCaskill-Stevens, MD, director of the NCI Community Oncology Research Program (NCORP), the NCI program supporting the trial. “The evolution of mammography technology provides us with an opportunity to fill in the gaps in our knowledge about two available breast cancer screening tests.” Although 3D mammography, being the newer technology, is likely to detect more findings that require follow-up, it is also likely to lead to more procedures and treatments. It is not known if this newer mammography technology is reducing a woman’s risk of developing an advanced cancer compared with 2D mammography. The TMIST trial aims to find out.”

“We need to determine if 3D mammography is better than 2D at finding the sort of breast cancers that are most likely to spread and kill women,” said ECOG-ACRIN study chair Etta D. Pisano, MD, vice chair of research in the Department of Radiology at Beth Israel Deaconess Medical Center and professor in residence of radiology at Harvard Medical School, Boston. “If a newer screening technology does not reduce the numbers of advanced, life-threatening cancers, then are we really improving screening for breast cancer?”

The primary outcome is to compare the proportion of women diagnosed with an advanced cancer within 4.5 years from enrollment in the randomized trial. TMIST researchers are collecting data on the results of every mammogram, on whether the imaging shows no signs of cancer, on findings suspicious of cancer, and whether a breast cancer has been diagnosed. Any medical follow-ups, such as more imaging or biopsies, are also being reported. TMIST researchers intend to follow all participants for breast cancer status, treatment, and outcomes from the time of randomization until the end of the study or at least until 2025).

In addition to data from mammograms, the trial is building a biorepository for future research on genetic markers for breast cancer by asking all participants to voluntarily submit blood samples and swabs of cells from inside the mouth (buccal cells). This data could, in the future, help women and their doctors decide the best ways to screen for breast cancer by evaluating their individual risk factors for developing the disease. TMIST researchers are also analyzing tissue collected from women who have biopsies during the trial because of mammogram findings that require follow up. Complete details of TMIST may be accessed here.

Healthcare centers in Canada launched a version (NCT02616432) of this clinical trial, called TMIST Lead-In, in October 2014 at the Sunnybrook Health Sciences Centre in Toronto. The patient cohort being recruited was 6,354 asymptomatic women under the age of 50 and enrollment has been reached. Data from TMIST Lead-In are expected to be rolled into the TMIST trial now under way in the United States.


  1. Updates in breast imaging: TMIST, guidelines and tomosynthesis technology - September 5, 2016.
  2. Canadian breast digital tomosynthesis clinical trial expands - March 24, 2017
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TMIST clinical trial comparing 2D and 3D mammography extends to United States.  Appl Radiol. 

By Staff News Brief| January 09, 2018

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