Oslo Screening Trial Finds Higher Cancer Detection With Tomosynthesis
Breast tomosynthesis, in conjunction with 2D breast screening exam, significantly increases cancer detection while reducing the number of false positives compared to 2D breast exam alone, according to a study published in Radiology, the Radiological Society of North America scientific journal. Hologic Inc. cited the study as an endorsement for tomosynthesis, a three dimensional mammography screening technology. The study, "Comparison of Digital Mammography Alone and Digital Mammography plus Tomosynthesis in a Population-based Screening Program," was conducted at Oslo University Hospital Ullevaal, and was based on 12,631 screening examinations in a large hospital in Norway. By using Hologic's 3D mammography technology in combination with a 2D mammogram, researchers found a 40% increase in the detection of invasive breast cancers, a 27% increase in the detection of all cancers (invasive and in situ cancers combined), and a 15% decrease in false-positive rates. Cancer detection increased across all breast tissue densities, from dense to fatty. Rob Cascella, Hologic's President and Chief Executive Officer said in the press release, "The Oslo trial is the first large-scale prospective study to show the additional cancers found with 3D mammography in combination with 2D mammography were invasive cancers—the very type of cancers we want to detect and treat early. 3D mammography is the best breast screening technology to date in that it finds significantly more invasive cancers while also reducing false positives. Most other imaging technologies for screening require users to compromise specificity (recall rate) for sensitivity (cancer detection). We believe the value of 3D mammography in breast cancer screening is most compelling." In regards to the study, the ACR issued comments citing concerns about the role of tomosynthesis in clinical practice. With average breast thickness of 54 mm in the study, radiation dose was 2.24 times that of mammography alone. Since detector size is not as large as available with full field digital mammography, women with larger breasts may require additional views for tomosynthesis of the entire breast volume, thus increasing radiation dose. Although the cancer detection rate was higher with tomosynthesis, it is not known if an equal incremental benefit would be realized in a second screening round. For the ACR, the study lacks adequate statistical information regarding subgroups of women in different ages, risk profiles, and parenchymal density. Reader performance among U.S. radiologists with varying practice patterns and expertise is also uncertain, and the study does not explore whether computer aided detection would provide any further benefit, and if reconstructed images could be used, in lieu of standard full field digital images, to reduce radiation dose. According to the ACR, there are practical issues relative to radiation dose, cost, efficiency, and benefit that need to be addressed before assessing the true value of tomosynthesis in clinical settings. For the full study, click here.