NEW YORK (Reuters Health) Jul 31 - Tomosynthesis plus conventional digital mammography for breast cancer screening reduces recall rates and may improve cancer detection rates, a retrospective study suggests.
"Tomosynthesis is a major advance in breast imaging," Dr. Liane E. Philpotts from Yale University School of Medicine in New Haven, Connecticut, told Reuters Health. "It will replace standard digital mammography with time as it is so much better."
Tomosynthesis provides 3-dimensional reconstructions of breast tissue, which can be viewed as sequential sections through the breast. It not only provides clearer images of some lesions, but it also reduces false-positive findings.
Dr. Philpotts and colleagues evaluated the performance of breast tomosynthesis by seeking to identify which patients experience the greatest reduction in screening mammography recall rates and evaluating the cancer detection rates.
The study included 6,100 patients who underwent tomosynthesis plus conventional digital mammography and 7,058 patients who underwent conventional digital mammography alone.
Overall recall rates were significantly lower in the tomosynthesis group than in the conventional imaging group (7.7% vs 12.0%; p<0 .01="" 30="" in="" july="" online="" p="" radiology.="" reported="" they="">
This advantage held true when women were stratified by the density of their breast tissue (i.e., scattered fibroglandular density, heterogeneously dense breasts, and extremely dense breasts) and for all age groups.
After adjusting for age, breast density, and breast cancer risk factors, tomosynthesis was associated with a 38% reduction in odds of recall compared with conventional mammography alone (p<0 .0001="" p="">
The greatest reductions in the odds of recall were seen in women younger than 40 (a 64% reduction; p=0.001) and by women with extremely dense breasts (a 60% reduction; p=0.002).
Cancer detection rates were 9.5% higher with tomosynthesis than with conventional imaging alone, but this difference failed to reach statistical significance. The researchers say 2,018 women would have to screened with tomosynthesis to detect one additional cancer beyond what would have been detected with mammography alone.
"The benefits in reducing recalls (false positives) along with better cancer detection will have a profound effect on screening mammography in terms of the shift of harms and benefits," Dr. Philpotts said. "As our study showed, it especially benefits younger women and those with dense tissues (where mammography has not done as well), and this could potentially save so many lives. Those who are skeptical about the benefits of mammography will really have to rethink. Basically, any argument against screening mammography using data from prior analog or even digital studies will be trumped by this data."
"Right now there is no reimbursement for tomosynthesis (although it is being worked on), so there is no financial benefit to the radiologists/facility," Dr. Philpotts added. "Yet the equipment is more expensive - my best estimate is roughly 50-100K more than a regular digital mammography unit."
A report on digital breast tomosynthesis (DBT) prepared by Australia's Department of Health and Aging in April 2013, while citing the advantages highlighted by Dr. Philpotts, points out some concerns as well.
"Although DBT has the potential to improve breast imaging, a number of issues need to be addressed prior to any widespread clinical implementation," the Australian paper says. (It's available athttp://bit.ly/14jjAgh.)
For one thing, DBT increases the radiation dose slightly compared to digital mammography - and in at least one study, when it was used in conjunction with digital mammography, the radiation dose was more than twice that of digital mammography alone. While the dose is still below limits set by the U.S. Food and Drug Administration, the report says, "this risk needs to be weighed carefully against the potential benefits and for acceptability to people who undergo screening."
In addition, there's no simple way to biopsy suspicious findings found only on DBT. "Developing an image-guided needle biopsy system was a key factor in the now widespread use of magnetic resonance imaging in breast imaging and will likely be an important component of implementing DBT," say the authors of the Australian report.
Also, the report's authors say - and as Dr. Philpotts pointed out - tomosynthesis is more expensive. "Some of the costs of implementing DBT are the price of the system itself, the cost of digital storage capacity to accommodate the large file size of DBT images and the cost of increased radiologist time due to the increased reading time for DBT images."
On the plus side, the Australian report points out, "DBT can be performed with half the compression force on the breast usually used for digital mammography without compromising the quality of the image."
Two of the six authors of the new report in Radiology have received consulting fees from Hologic, which manufactures breast tomosynthesis equipment.
SOURCE: http://bit.ly/13APo8Z
Radiology 2013.
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