BBI

The long-awaited results of a study comparing digital mammography with film mammography conducted by the American College of Radiology Imaging Network (ACRIN; Philadelphia) were released in mid-September and simultaneously published in the New England Journal of Medicine’s online special edition.

According to the ACRIN Digital Mammographic Imaging Screening Trial (DMIST) – which ACRIN called one of the largest breast cancer screening studies ever performed – the results indicate that digital mammography detected “significantly” – up to 28% – more cancers than screen film mammography in women 50 and younger, premenopausal and perimenopausal women, and women with dense breasts.

Overall, however, the study showed no “statistically significant” superiority for digital mammography technology over film, a conclusion with two edges to it. While digital was no better than film, it was at least equivalent overall, and better in the specified cases.

Film mammography units use film to both capture and display the image. Digital mammography takes an electronic image of the breast and stores it directly in a computer, allowing the recorded data to be enhanced, magnified or manipulated for further evaluation, and stores it directly in a computer. Those supporting the digital technology have touted it as potentially improving earlier diagnosis, as well as reducing the storage requirements demanded by film. The electronic image also can be printed on film.

ACRIN said the sensitivity of film mammography is “somewhat limited in women with dense breasts,” and that this is a population of women at higher risk for breast cancer.

“The groups of women who may benefit from digital technology are those in which standard mammography has been less effective. These results will give clinicians better guidance and greater choice in deciding which women would benefit most from various forms of mammography,” said Etta Pisano, MD, Kenan Professor of Radiology and Biomedical Engineering at the University of North Carolina (Chapel Hill), director of the Biomedical Research Imaging Center at UNC and member of the UNC-Lineberger Comprehensive Cancer Center.

“Of particular interest, the cancers detected only by digital mammography are the types of cancers that must be detected early to save more lives through screening.”

Pisano told The BBI Newsletter that, with these results, ACRIN is recommending that women in that subgroup of younger women “should probably get screened with digital.”

She added:“Since there was significantly better diagnostic accuracy, mainly in the number of cancers detected as opposed to an increase in specificity ... I would hope that more women would be able to get digital [mammography].” She said put the current group of women being screening with digital mammography at “only 8%.”

Asked if she was surprised by the results, she said, “Not in the slightest.”

And as to the finding that digital did not show significantly improved detection above film for the overall population, she said she wasn’t disappointed, since equivalence of the two systems was shown.

Bruce Hilman, MD, network chair of ACRIN, said, “I am very proud of the accomplishments of the DMIST researchers. The DMIST team of clinicians and scientists did a truly miraculous job in completing this complex trial quickly and producing these important results. This landmark trial, along with others currently being conducted by ACRIN, will influence the appropriate care for women everywhere.”

GE Healthcare (Waukesha, Wisconsin), Fuji Medical Systems (Stamford, Connecticut), Fischer Imaging (Denver) and Hologic (Bedford, Massachusetts) digital mammography systems were tested in the trial.

“GE is very grateful for being the leading participant in the trial,” said Vincent Polkus, mammography advanced application product manager, told BBI following a presentation at an ACRIN meeting at the Ritz-Carlton Pentagon City (Arlington, Virginia). “This is an important study to determine the clinical effectiveness of full-field digital compared to the existing gold standard of care, which was screen film.”

He added, “The results, I think, were very impressive, that in fact there was a group of women that was particularly benefited or would benefit greatly from the full-field digital technology ... digital was considered to be equivalent, and for a new technology to come on line as quickly as digital did, and to be even judged equivalent to the existing standard of care is a huge success.”

Polkus said the “scientific rigor” of such screening trials is “unquestioned.”

He said that what was “particularly exciting” is that GE chose its digital mammography technology for the trial for what it could do today, but also chose it, he said, “because we knew that we could make it better.”

Polkus added: “We could improve its ability to detect cancers, and in fact, even since the trial started in 2001, we have made significant changes to the technology that we believed would perhaps be important in the results.”

Hologic issued a statement following the release of the DMIST study by the NEJM, with Chairman and CEO Jack Cumming saying the company is “pleased with the results. The most promising finding involved a subcategory of women involved [the] subcategory of women including women under 50, women with dense breasts and premenopausal or perimenopausal women, which represented 65% of the study population, [and] digital mammography had statistically greater diagnostic accuracy than film-based systems.”

The National Electronic Manufacturers Association (Rosslyn, Virginia), which calls itself the largest association of medical imaging companies in the world, said, “The study shows that digital mammography is a win-win technology that significantly improves cancer detection in key groups of women and makes big improvements in productivity because digital images are easier to access, adjust, store and retrieve.”

The association also said: “Digital mammography can also [help] move the U.S. healthcare system into the age of IT, the electronic health record and the efficiencies that information technologies offer.”

GE’s Polkus said that digital technology holds promise for applications such as 3-D imaging, combining other imaging technologies such as ultrasound, or positron emission tomography with full-field digital.

The Center for Biostatistics at Brown University Medical School (Providence, Rhode Island) developed the study’s statistical design and analyzed the results. Starting in October 2001, DMIST enrolled 49,528 women at 33 sites in the U.S. and Canada who had no signs of breast cancer.

Women in the trial were given both digital and film mammograms. Mammograms were interpreted independently by two different radiologists. ACRIN said that the participants breast cancer status was determined through available breast biopsy information within 15 months of study entry or through follow-up mammography 10 months or later after study entry.

According to the NCI, in the U.S., breast cancer is the most common non-skin cancer, and the second-leading cause of cancer-related death in women. An estimated 211,240 women will be diagnosed with breast cancer and an estimated 40,410 women will die of the disease in the U.S. in 2005.

The trial, which began in 2001, was funded by the National Cancer Institute (NCI; Bethesda, Maryland) and conducted by ACRIN, which describes itself as a “cooperative group” that has no continuing membership. The organization said that anyone is welcome to join in its trials if meeting the “qualifying criteria” for participating.

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