The Food and Drug Administration cleared the next step Monday for a new three-dimensional mammogram device purported by the device maker Hologic to more precisely detect breast lesions and reduce the number of follow-up breast cancer screenings when used in conjuction with conventional digital mammograms.
"This is a major advance that we have been working on for years," said Dr. Daniel Kopans, director of the breast imaging center at Massachusetts General Hospital in Boston, which holds the patent to the device. "It will aid in detecting more cancers earlier, and reduce the false positive callbacks."
The FDA panel that reviewed the device sent Hologic an initial letter accepting the device into its next phase for review. And while experts agreed more precise methods of detecting breast cancer are necessary, many said there's not enough evidence yet to show whether the new device can save lives.
"The real issue here is not which test can find the most cancers, it's about which test can find the right cancers," said Dr. Gilbert Welch, professor of medicine and community and family medicine at Dartmouth Medical School in Hanover, N.H. "Just because you find more and more, more of what you're finding might not be important."
Welsh said he worried earlier detection of benign masses that might not develop into cancer could result in unnecessary treatment in otherwise healthy women.
Long-term randomized trials comparing conventional mammograms to 3D mammograms will be the best way to know whether the new device will actually save lives, Welch said.
"Mammography, even digital, is far from perfect," said Dr. Emily Conant, professor and chief of the division of breast imaging at Hospital of the University of Pennsylvania.
Conventional mammogram screenings of women over age 40 could result in false diagnoses and a greater challenge in detecting clusters that actually develop into breast cancer, Conant said.
A conventional mammogram overlaps two X-rays taken from different angles of the breast, said Conant, at times making it difficult to detect whether a mass is truly cancerous.
The 3D mammogram device -- called tomosynthesis -- captures several images of a woman's breast at many different angles.
An FDA panel reviewed three studies -- two of which were conducted by Hologic -- that suggested the device could pick up more suspicious lesions when used in combination with conventional mammography. However, it's unclear whether the lesions were determined to be cancerous.
But according to Dr. Neil Brooks, a family practitioner in Vernon, Conn., while the combined approach may work well for women at an increased risk for breast cancer, it may prove unnecessary for "women who are otherwise well," he said.
"We pile on technology after technology without ever really understanding the full costs and benefits," Brooks said.
"The threshold to introduce new tests in this country is too low," Welch said. "I worry about the general mindset that a new test that can see more and finds more cancers is seen as an improvement."
Data submitted by Hologic to the FDA panel suggested the combination testing offered twice the level of radiation as conventional mammography alone.
And, while the studies submitted to the FDA suggested a reduced rate of follow-up screenings in women, the studies offered no indication that the combination of tests could detect breast cancer not picked up by conventional mammograms.
"There still needs to be additional work to keep the radiation dose of screening studies very low and figure out which women will most benefit from this new technology," said Conant.
The panel subsequently sent Hologic a so-called approvable letter, subjecting the company to manufacturing inspections before final approval.
Hologic refused to offer a timeframe for approval but Jim Culley, Hologic's director of marketing told ABCNews.com he's confident of approval, since the company has been manufacturing and selling the device to other countries for the past two years.
Indeed, tomosynthesis may offer better imaging for breast cancer detection than seemingly older technologies, but many experts said until it proves better than the current digital mammogram available, it may be a hard sell.
"Without stronger evidence, [tomosynthesis] will not become widely available to patients," said Dr. Etta Driscoll Pisano, chief of breast imaging and dean of the University of South Carolina College of Medicine. "It is likely to reduce false positives. It may find more cancers, but maybe not.
"I hope the comparative effectiveness studies are done to figure it out," she said.