Digital mammography finds more cancers than film in women under 50

Digital mammography is more accurate than film in detecting cancer in women under age 50, those who have dense breasts, and in pre- and perimenopasual women, according to the long-awaited results from the Digital Mammography Screening Trial (DMIST).

The five-year DMIST trial, conduced with a $22 million grant from the National Cancer Institute, was conducted under the auspices of the American College of Radiology Imaging Network. The study involved 49,500 women and devices from four vendors, with initial and follow-up mammograms conducted at 33 sites in the U.S. and Canada. Study results were published online by the New England Journal of Medicine (www.nejm.org) and simultaneously announced at the fall ACRIN meeting on Sept. 16.

Industry watchers familiar with both technologies had predicted that the trial would be a draw in terms of cancer detection. And while digital and film did perform similarly in the total study population, digital proved statistically better in the three patient subsets. That finding surprised even Dr. Emily Conant, chief of breast imaging at the University of Pennsylvania Medical Center in Philadelphia and one of the study's coauthors.

"I think those of us who use digital knew it would prove to be better - we didn't know it would be significantly better," she said.

Conant noted that of the 49,500 women studied, about 65% fell into one of the three groups where digital excelled: under 50, with dense breasts, and pre- or perimenopausal.

"That's a very high percentage, which says that digital mammography is valuable in detecting cancer in a large number of women undergoing screening," she said.

Digital has additional advantages over film. Digital images are easier to access, store, and transmit, and can be acquired at a lower radiation dose without compromising quality, according to the study.

DMIST demonstrates that digital mammography is a "win-win," said Bob Britain, vice president of medical products at the National Electrical Manufacturers Association in Washington, DC.

"Digital mammography improves cancer in key groups of women and allows improvements in productivity," he said.

Whether the study results will encourage increased adoption of digital remains to be seen. Digital systems cost about $450,000, and many breast centers are strapped for cash, given the low reimbursement rates they receive for exams. That hasn't deterred some sites from investing, however. In 2004, an estimated 410 digital mammography units shipped to U.S. customers, compared to about 200 in 2003.

"Cost remains a big factor," Conant said. "Individual sites will have to decide how much it is worth. But digital is the wave of the future, and this study is just the beginning."