A landmark breast cancer screening trial involving Rhode Island Hospital and 32 other sites nationwide has shown that digital mammograms detect up to 28 percent more cancers than traditional film images in younger women and those with dense breasts.
The trial, led by the American College of Radiology Imaging Network (ACRIN) in conjunction with the Center for Statistical Sciences at Brown Medical School, is important because it confirms that digital equipment is, indeed, worth the extra cost, said Dr. Barbara Schepps, director of the Anne C. Pappas Center for Breast Imaging at Rhode Island Hospital and a clinical professor at Brown.
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Rhode Island Hospital has one of only two digital mammography machines in the state, Schepps said – the other is at Women & Infants Hospital. Yet even her center’s machine could only be acquired thanks to a donor, she said, and the two other machines there still use film.
The reason is quite simple: cost. A digital unit goes for $400,000 to $500,000, she said; a traditional machine costs about $80,000. Even at that lower cost, radiologists lose money on the procedures, plus they’re the “number-one” reason for malpractice claims, Schepps said.
Only about 50 sites still do mammograms – which are recommended annually for women over 40 – and except for urgent cases, it takes months to get an appointment. At Rhode Island Hospital, Schepps said, a caller today would get a date in January.
Mammograms are crucial to detecting breast cancer, which is the most common non-skin cancer and the second leading cause of cancer-related death among U.S. women, according to the National Cancer Institute. This year, an estimated 211,240 women will be diagnosed with breast cancer, and 40,410 will die from it.
Between 1989 and 1999, Schepps noted, stepped-up use of mammography reduced breast cancer mortality rates by 25 percent. Yet for many women under 50 and around menopause, and others with dense breasts, the images on film aren’t quite good enough to detect small tumors.
For some time, the word among radiologists had been that digital mammography would change that. That’s because like digital photos, the images can be manipulated to adjust the contrast and to zoom in on a particular section. The images can be quality-controlled and redone immediately if there’s a problem, and they can be shared electronically with colleagues, as needed, and with the woman’s physician.
Still, Schepps said, the machines would only be worth the extra investment – and the accompanying investment in technology to store and transmit the images – if digital mammography was really proven to work better. The question was pressing enough that ACRIN enlisted partners across the nation to try to answer it.
A total of 49,528 women were enrolled, including 642 in Rhode Island; it was one of the largest breast cancer screening studies ever performed. Brown’s Center for Statistical Sciences developed the study’s statistical design and analyzed the results.
The women, whose median age was 54, had no signs of breast cancer when they enrolled. Each was given both digital and film screenings, and two separate radiologists interpreted the results. Follow-up mammograms and, when relevant, biopsy results determined the women’s breast cancer status within 15 months of entering the study.
As reported in the New England Journal of Medicine on Sept. 16, the study found that for older women – for whom film mammograms already work very well, Schepps said – digital units worked just as well, though no better. For the typically harder cases, however – women 50 and under, pre- and perimenopausal women, and women with dense breasts – digital mammograms were substantially better, though still not perfect.
“Neither film nor digital mammography is able to catch every cancer,” said Constantine Gatsonis, professor of community health and applied mathematics at Brown and an author of the journal article. “So this study data can be used to develop and improve mammography in the coming years, and that is good news for women’s health.”
Schepps said she expects the study to dramatically boost demand for digital mammograms, and it will certainly increase radiologists’ desire to go digital. But the costs of the machines and of the computer technology to support them may still be prohibitive.
“It’s exorbitantly expensive,” she said, and philanthropy is likely to continue to be key.
