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TMIST trial to compare two types of digital mammography
An NCI-supported trial will compare tomosynthesis — or 3-D mammography — with conventional 2-D mammography for the screening of breast cancer in asymptomatic women.
“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,” Worta McCaskill-Stevens, MD, director of the NCI Community Oncology Research Program (NCORP), said in a press release. “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.”
Tomosynthesis is a newer technology that has been shown to detect more findings that require additional follow-up. However, that screening approach also is associated with an increased number of procedures and treatments.
The Tomosynthesis Mammographic Imaging Screening Trial (TMIST) is the first randomized trial designed to determine if one digital mammography methodology is superior to the other.
The trial is expected to enroll 165,000 asymptomatic women aged 45 to 74 years, and nearly 100 mammography clinics in the United States are expected to participate.
Participants will be asked to voluntarily submit blood samples and swabs of buccal cells for a planned repository to be used for future research into genetic markers of breast cancer.
HemOnc Today spoke with McCaskill-Stevens about why a trial like this is needed and the potential implications of the results if they show a clear benefit for one modality compared with the other.
Question: Can you describe the differences between these two screening modalities?
Answer: The Digital Mammography Screening Trial (DMIST) — completed in 2005 — compared plain film and digital mammography, thus, providing the basis for the use of 2-D mammography in current screening practice. In this nonrandomized trial, 2-D was shown to improve the detection of radiographically dense breast tissue among pre-and perimenopausal women. Tomosynthesis is a newer technique that reconstructs a series of thin images. It may provide an advantage in that it can address some of the overlap of structures in 2-D and, therefore, give potentially better imaging, particularly for dense breasts. What we know about tomosynthesis — in the absence of a randomized clinical trial — is that it has been reported to decrease recall rates. Some studies have looked at the interval breast cancers that may be detected, but most of the data that we have available have come from one vendor, Hologic, to which the first FDA approval was issued in 2011.
Q: Why is a trial like this needed?
A : With the advent of new technologies, we have not had anything to provide additional evidence in the area of screening for breast cancer. The use of 3-D for breast cancer screening is at a rate low enough across the United States that the timing for a trial like this could not be better. This randomized trial has a design that gives us a most rigorous approach to answer questions related to reducing rates of advanced cancers over time and overdiagnosis. The establishment of a biorepository that includes tissue from all biopsies — benign, premalignant and invasive — has the potential to begin to personalize screening for breast cancer.
Q: How will the trial be conducted?
A: Women are being told about the opportunity to enroll in the trial when they schedule a routine screening mammogram. Once enrolled, women will be randomly assigned to 2-D or 3-D mammography. Although the majority of women enrolled in the trial will be screened annually, postmenopausal women with no high-risk factors will be screened biannually. We will collect data on the results of every mammogram, whether the imaging shows no signs of cancer, findings suspicious of cancer or a breast cancer. All medical follow-ups, including additional imaging and biopsies, will also be reported. In addition, women will be asked on a one-time basis to provide a blood specimen for the biobank. The significance of this specimen collection is that it is performed concomitantly with screening and ultimately will provide researchers with molecular information that can be used to more precisely guide breast cancer screening in the future.
Q: When might results become available?
A: We intend to follow all participants for breast cancer status, treatment and outcomes from the time of randomization until at least 2025.
Q: What are the potential implications of the results if the trial does show a clear benefit for one modality ?
A: There are several implications. One is that it will help inform our understanding of risk and frequency of screening for different levels of risk of developing breast cancer. Second, it will help us identify those tumors for which we know there is overdiagnosis. Third, it will provide an opportunity to assess the cost of screening using these two modalities.
Q: Is there anything else that you would like to mention?
A: Mammography has been a very provocative topic, and each woman must think on her own terms about when to undergo screening and how often to be screened. This research is a great step forward and is consistent with our goals of more precisely individualizing cancer prevention. – by Jennifer Southall
Reference:
Pisano ED, et al. N Eng J Med. 2005;doi:10.1056/NEJMoa052911.
For more information:
Worta McCaskill-Stevens, MD, can be reached at National Cancer Institute, BG 9609 MSC 9760, 9609 Medical Center Drive, Bethesda, MD 20892; email: mccaskiw@mail.nih.gov.
Disclosure: McCaskill-Stevens reports no relevant financial disclosures.