Widespread adoption of digital mammography for breast cancer detection will hinge on results from the National Cancer Institute's large trial comparing the technology with film screening, according to lead investigator Etta Pisano, MD, University of North Carolina at Chapel Hill.

Initial data from the 49,428-patient, 34-center U.S. and Canadian study likely will be released next spring or summer. Pisano's comments came during a June 10 briefing on an Institute of Medicine report, "Saving Women's Lives: Strategies for Improving Breast Cancer Detection and Diagnosis," in Washington, D.C.

The trial includes digital mammography systems from GE Healthcare, Fischer Imaging, Hologic and Fuji (¹ Also see "Digital Mammography Firms May Meet FDA Requirements Through NCI Trial" - Medtech Insight, 5 March, 2001., p. 11). In 2000, GE's Senographe 2000D became the first such system to earn FDA approval.

The IoM report notes that digital platforms cost $350,000-$500,000 versus $80,000-$90,000 for screen-film units. If the NCI-supported study proves digital screening to be more effective, "it will be a cost to the system to replace film," Pisano acknowledged.

Moreover, "although CMS will reimburse health care providers for the use of digital mammography for screening mammograms, many insurance companies will not," the report adds, citing BlueCross BlueShield and the Kaiser Foundation in particular.

Those positions may be revised if "new evidence indicates clear advantages of digital over screen film mammography, such as results from the [NCI] trial expected in 2005," the report states.

At the IoM event, speakers added that CMS' current reimbursement rates for mammography as a whole are insufficient and have contributed to an 8.5% decline in operational screening centers over the last four years.

Jean Lynn, RN, George Washington University Breast Care Center, estimated the current reimbursement rate for mammography at $83. The rate does not cover mammography performance costs of $87 for a free-standing clinic and $105 for a hospital, she explained.

Lynn raised concern with new, expensive technologies that would reach far beyond CMS' reimbursement rate. "What we need to consider, as we're improving technology, is to make sure that women will have it available as it is developed."

Regarding new technologies to aid breast cancer detection, the report's recommendations focus on ways to enhance mammography rather than replace it.

For example, stakeholders should work on "improving the overall quality of mammography interpretation and encouraging the development and dissemination of adjunct technologies," such as computer-aided detection (CAD), "that would further improve mammography," the report says. In 1998, FDA approved the first CAD system, R2 Technology's ImageChecker .

Although a recent CAD study did not find statistically significant changes in recall or breast cancer detection rates, the IoM report cites the technology's "potential to bring the performance level of general radiologists to that of breast imaging specialists" (² Also see "CAD Mammography Benefits Questioned By U-Pitt Researchers" - Medtech Insight, 9 February, 2004., p. 12).

To replicate the desired effects of CAD, the report suggests U.S. use of "physician extenders," trained non-physicians to pre-screen or double-read mammograms with a radiologist.

The practice occurs in Europe, along with "the organization of regionalized services in which mammograms are read by breast imaging specialists at a central location," the report notes. IoM credits practicing countries with lower false-positive rates.

In the U.S., the report discusses the workload crisis facing breast cancer imaging, with fewer radiologists joining the field each year in light of poor financial opportunities stemming from low reimbursement and high malpractice rates. The report argues that physician extenders could increase efficiency.

FDA maintains quality control oversight of mammography centers following the 1992 passage of the Mammography Quality Standards Act. The agency released the 2003 report on adverse events and corrective actions May 27, reporting one revocation of accreditation and one suspension of accreditation.

Perhaps reflecting the workload crisis, approximately 39.5% of U.S. women aged 40-64 did not receive a mammogram in 2002.

Despite the advent of new screening modalities for breast cancer, IoM's Janet Joy, PhD, stressed the implausibility of "one giant breakthrough that wipes mammography off the landscape." Instead, she anticipated "a lot of incremental approaches. For example, MRI could be very useful for high-risk women."

The IoM report supports Joy's prediction. "Because technologies that completely replace mammography are unlikely to reach the market - at least within the next 10 years - organizations will be faced with the challenge of adopting technologies that will be used in conjunction with existing modalities."

Pisano mentioned an ongoing trial studying the use of MRI in high-risk women who already have been diagnosed with cancer in a breast. The 1,000-patient, 15-center trial will screen the opposite breast.

Soon to open for enrollment, a separate study will compare ultrasound screening with mammography for high-risk women, Pisano added.

Both studies, sponsored by the National Cancer Institute and a clinical trial group called the American College of Radiology Imaging Network, will have data available within five years, "probably sooner for the MRI trial," she said.

Should results from the MRI trial prove beneficial, the technology still will not supersede mammography as the gold standard in breast imaging, Joy asserted. "I don't know if any experts think it would be useful for screening average women.... The accuracy of it is not going to be that good."

In general, trends in new technology adoption can appear arbitrary and beyond the bounds of FDA approval, IoM writes. The report refers to TransScan's T-Scan 2000 transpectral impedance scanner as a mammography adjunct that, though PMA-approved, did not succeed in the U.S. market (³ Also see "TransScan TS-2000 Mammography Adjunct Per-Procedure Cost Is Under $100" - Medtech Insight, 26 April, 1999., p. 11).

The device maps the physiological impedance of breast tissue using a one-volt current, working on the theory that electrical impedance of malignant tissue is lower than for normal tissue. The adjunct was approved in 1999, "but four years later the manufacturer had not sold a single machine in the U.S."

Edward Penhoet, PhD, Gordon and Betty Moore Foundation, and Diana Petitti, MD/MPH, Southern California Permanente Medical Group, co-chaired the 16-member IoM panel that produced the report, which follows a 2001 version, "Mammography and Beyond."

IoM Breast Cancer Detection Report Promotes Mammography Adjunct Tools

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