Mammograms: Digital vs. Film

January 5th, 2014

Article By David Armstrong for The Wall Street Journal

For the 23 million U.S. women who get mammograms each year, there is an increasingly urgent question: digital or film?

Interest is growing in the digital version of the breast-cancer screening test, driven in part by a study last fall in the New England Journal of Medicine that said digital was better for some women. The findings quickly became a marketing tool for makers of digital-mammography machines and hospitals that have them. Sales of the machines have been rising, with one major manufacturer citing digital equipment as the driving force behind record second-quarter revenue.

But some hospitals and doctors are concerned that the advantages of digital are being overestimated and may be causing women to delay getting a mammogram until digital machines arrive in their area. Still only about 11% of the 8,800 U.S. mammography facilities are estimated to have digital.

The advice from doctors: Don’t wait, especially if you are in one of the groups for whom digital has no demonstrated advantages. The study found that digital was better at detecting cancer only for premenopausal women, those under 50 years old, or those who have dense breasts. The majority of women who get mammograms are over 50, and looking at the 40,000 women in the study as a whole, the new technology was found to be no better than film overall.

Past research on the use of digital-mammography machines, which were first approved by the federal Food and Drug Administration in 2000, showed no overall benefit compared with film, though the studies may have been too small to identify benefits in subgroups.

“One thing that concerns radiologists is that women will think film isn’t good,” says Kathleen Brant, chairwoman of the breast imaging and intervention division at the Mayo Clinic in Rochester, Minn. “Our position is it is best to have a mammogram of any kind rather than no mammogram.”

Dr. Brant says a lot more women are asking their doctors about digital. At the Mayo Clinic, which has both kinds of machines, women who fall into one of the categories shown to benefit from digital are generally referred for a digital exam, she says. But most women still receive film mammograms at the facility.

The Michigan Cancer Consortium — a network of hospitals, insurers and private and public health groups — issued a position paper on digital mammography last month in response to the large number of questions it was getting from patients and hospitals. The consortium advised that “although digital mammography can detect cancers that might be missed by film mammography,” that isn’t true for all women. The organization recommended that when both types of screening are available, the decision be tailored to each woman.

The FDA may soon make it easier for digital-mammography makers to bring new machines to the market. An advisory committee voted last week to put digital-mammography machines in a class where manufacturers must prove only that their equipment is substantially similar to products already on the market. Currently, manufacturers often have to conduct costly clinical trials testing safety and efficacy before gaining approval for the machines. The committee action still needs agency approval.

For hospitals and physicians, there is another reason to favor digital mammography. The insurance reimbursement for digital screening is much higher. The national average for Medicare reimbursement (which many insurance companies base their own rates on) is $85.65 for film mammography and $135.29 for digital. For years, mammography has been a money loser for many hospitals. While the digital machines are as much as four times as expensive to purchase, over time the higher reimbursement rates could produce more-profitable returns.

Many breast-cancer specialists believe it is only a matter of time before digital mammography is the standard screening tool. That is largely because all of radiology is going digital, from magnetic-resonance-imaging scanners to CT machines. One major maker of digital-mammography equipment, Hologic Inc. holx +1.14% of Bedford, Mass., last month reported a 46% increase in revenue for the second-quarter compared with the year prior, citing strong sales of its digital-mammography equipment. Other big makers of the digital equipment include Siemens AG si -0.28% and General Electric Co. ge -0.07%

Both digital and film mammograms take X-ray images of the breast. The traditional method uses film to capture and display the image. Digital mammography is filmless, and captures the X-ray as an electronic image. The images themselves are similar, but one potential advantage of digital is that it allows radiologists more leeway to magnify or enhance the image. Some radiology centers say digital equipment delivers less radiation. But most experts note that the level of radiation in film mammography is already extremely low.

Digital images are also easier to store, and can be quickly shared among specialists at different locations. Storing large numbers of film images of mammograms can be expensive. As a result, “ultimately the cost will be less” with digital, says Max Wicha, the director of the University of Michigan Comprehensive Cancer Center.

The issue of whether digital mammograms are actually better for detecting cancer than traditional film X-rays remains a matter of debate. An editorial accompanying the New England Journal of Medicine study concluded the “advantage offered by digital mammography appears to be limited to a minority of women who undergo screening, since most women who get a mammogram are over 50 and post-menopausal.”

The U.S. Preventive Services Task Force, a government appointed panel of health experts, recommends women over 40 undergo a mammogram at least every other year. The task force found the screening benefit was greatest for women aged 50 to 69. A spokeswoman says the task force is scheduled to release an update of its breast-cancer screening recommendations next year.

The American College of Radiology has no position on digital vs. film, and officials there say it is more important that women get at least some form of mammography regularly.

The New England journal study, which was funded by the National Cancer Institute, didn’t look at whether or not digital screening resulted in fewer women dying from cancer, notes Mark Ebell, a physician and researcher at Michigan State University in East Lansing, Mich., who is an expert on evidence-based medicine. “The benefit may be so small that is not cost-effective,” he says. The study researchers say they are now conducting a cost-effectiveness analysis of the digital technology.

Dr. Ebell worries the higher cost of digital mammography will make the screening unaffordable for women without health insurance.

“There is no reason to get any more of these [digital] units because they haven’t been shown to have a benefit for the overall population,” says Carolina Hinestrosa, an executive vice president for National Breast Cancer Coalition, a nonprofit group in Washington that lobbies for more federal funding of breast-cancer research. “From a public-health standpoint, we don’t think it is a wise thing to do.”

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