3D breast screen may cut recall rates

3D breast screen may cut recall rates

3/12/2013

CHICAGO -- Digital breast tomosynthesis may reduce recall rates and increase cancer detection compared with digital mammography, researchers reported here.

In their observational study, the newer screening modality was associated with a significant 15.6% reduction in recall rate compared with traditional mammography (P=0.001), according to Emily Conant, MD, of the Hospital of the University of Pennsylvania in Philadelphia, and colleagues.

Tomosynthesis was also tied to a 22.7% increase in cancer detection, although the finding didn't reach statistical significance, they reported at the Radiological Society of North America meeting.

"Tomosynthesis is evolving, and this is the beginning of an exciting platform that will address many issues ... it is an improvement on 2D mammography," Conant said during an RSNA press briefing.

While digital mammography is still the gold standard of breast cancer screening, results from early studies using tomosynthesis as a first-line screening tool have been promising, Conant said.

In fact, some centers have been using the technology first-line because it can create a 2D image as well as the 3D image -- although the latter tends to bring reimbursement challenges, experts said.

Because digital mammography is notorious for its false-positive findings and the anxiety these can induce, researchers said tomosynthesis may be able to help fix that problem by diminishing recall rates and increasing detection rates.

The STORM study, published earlier this year in The Lancet Oncology, found increased detection rates and lower recall rates with the addition of 3D imaging to the typical 2D view.

And one randomized Norwegian study reported in Radiology last January found that cancer detection rose by 27% and false-positives fell by 15% when combining tomosynthesis with conventional imaging.

Since October 2011, Conant and her colleagues have used tomosynthesis as their first-line screening tool for breast cancer.

They compared the results of 15,632 of those scans with 10,752 digital mammographies that had been done in the year before tomosynthesis was implemented.

They found that recall rates were significantly lowered by using tomosynthesis compared with standard 2D digital mammography (8.77% versus 10.39%), which translated to a 15.6% reduction in recall rate (P=0.001).

They also found that cancer detection rates were higher with tomosynthesis (5.25 versus 4.28 per 1,000 scans), leading to a 22.7% increase in cancer detection, although the finding wasn't statistically significant.

Specifically, Conant noted that there was a 30.1% increase in detection of invasive cancers.

And PPV1 rates, which reflect the true positive yield of recalled cases, were higher with tomosynthesis than with standard mammography (5.9% versus 4.12%), which reflected a 45% increase in PPV1.

Conant and colleagues also examined their findings by breast density and found diminished recall rates for all levels of density, with the exception of an increased recall rate among those with highest breast density (7.92% to 9.18%).

All groups, however, had an increase in cancer detection rates, she said.

Conant noted that the technology is particularly good at picking up invasive lobular carcinomas -- a major shortcoming of 2D mammography.

However, the challenge with the new imaging modality is the radiation dose, she said. Radiation exposure is twice as high with tomosynthesis as with digital mammography, although it still falls well under standards for radiation exposure, Conant said.

"The cost is not monetary at our site," Conant said. "Right now, the dose is the biggest cost."

But many imaging specialists are still inclined to use the technology. Debra Copit, MD, director of breast imaging at Albert Einstein Medical Center in Philadelphia, who was not involved in the study, said her center screens all women with tomosynthesis "because we believe in it."

She added the technology is now available so that a reimbursable 2D image can be gleaned from the 3D image so radiologists don't have to run a separate scan, thus increasing radiation exposure.

Copit concluded that the current study adds to the literature that "clearly shows a significant decrease in recall rates and a simultaneous increase in detection."

That said, it's not the "be-all, end-all" of breast cancer detection, she said.

A large, randomized, controlled trial is currently underway to compare digital mammography with tomosynthesis on a wider scale.

 

Source: MedPage Today: http://www.medpagetoday.com/MeetingCoverage/RSNA/43233