ParticipantsMarije F. Bakker, PhD, Utrecht, Netherlands (Abstract Co-Author) Grant, Bayer AG; Software support, Volpara Health Technologies Limited
Stephanie V. de Lange, Utrecht, Netherlands (Presenter) Research Grant, Bayer AG; Software support, Volpara Health Technologies Limited
Rudolf M. Pijnappel, MD,PhD, Haren, Netherlands (Abstract Co-Author) Research Grant, Bayer AG
Ritse M. Mann, MD, PhD, Nijmegen, Netherlands (Abstract Co-Author) Researcher, Siemens AG Researcher, Seno Medical Instruments, Inc Researcher, Identification Solutions, Inc Researcher, Micrima Limited Researcher, Medtronic plc Scientific Advisor, ScreenPoint Medical BV Scientific Advisor, Transonic Imaging, Inc Stockholder, Transonic Imaging, Inc
Claudette E. Loo, MD, Amsterdam, Netherlands (Abstract Co-Author) Nothing to Disclose
Bob Bisschops, Dordrecht, Netherlands (Abstract Co-Author) Nothing to Disclose
Marc Lobbes, MD, Maastricht, Netherlands (Abstract Co-Author) Nothing to Disclose
Mathijn D. De Jong, MD, 's-Hertogenbosch, Netherlands (Abstract Co-Author) Nothing to Disclose
Katya M Duvivier, MD, Amsterdam, Netherlands (Abstract Co-Author) Nothing to Disclose
Jeroen Veltman, MD, Hengelo, Netherlands (Abstract Co-Author) Nothing to Disclose
Wouter B. Veldhuis, MD, PhD, Utrecht, Netherlands (Abstract Co-Author) Nothing to Disclose
Carla H. van Gils, PhD, Utrecht, Netherlands (Abstract Co-Author) Software support, Volpara Health Technologies Limited
PURPOSE To evaluate the effect of supplemental MRI for women with extremely dense breasts within a population-based screening program. METHOD AND MATERIALS Between 2011-2015, we randomized 40,373 screening participants (aged 50-75) with a negative screening mammography and extremely dense breasts (ACR category 4 by Volpara software) to (an invitation for) supplemental 3.0-T MRI at 8 sites (intervention arm; n=8,061) or mammography screening only (control arm; n=32,312). The difference in interval cancers after the first (prevalent) screening round, during the two-year screening interval, was investigated by intention-to-treat (ITT) analysis, and by complier-average causal effect (CACE) analysis to account for noncompliance. The performance of the incident screening rounds was investigated as well. RESULTS In the intervention arm, 4,783 (59%) underwent MRI examination. Cancer detection rate was 16.5/1000 screens [95%CI:13.3-20.5]. For this, 9.5% of women were recalled (6.3% with biopsy). Positive predictive values are 17.4% [95%CI:14.2%-21.2%] (recall) and 26.3% [95%CI:21.7%-31.6%] (biopsy). In the intervention arm, cancers were more frequently stage 0-I than in the control arm (82.8% vs 41.6%, p<0.001). With ITT analysis, the interval cancer rate was 4.98/1000 women in the control arm and 2.48/1000 women in the intervention arm, leading to a reduction of 2.50/1000 women [95%CI:0.98-3.71]; p<0.001. With CACE analysis, this reduction was 4.22/1000 women [95%CI:2.01-6.43]. Preliminary results of the incident screening rounds showed that 3,548 women had again undergone (at least one) mammographic screening with a negative result. Supplemental cancer detection rate was 5.3/1000 screens [95%CI:3.4-7.7]. For this, 2.8% [95%CI:2.4%-3.4%] of women were recalled for further diagnostic work-up. At the meeting, results on cost-effectiveness will be presented as well. CONCLUSION Supplemental MRI screening in women with extremely dense breasts results in statistically significantly fewer interval cancers. In subsequent rounds, both the cancer detection rate and the false-positive rate decrease. CLINICAL RELEVANCE/APPLICATION There is a heated debate on the value of supplemental screening in women with dense breasts. The DENSE trial is the first randomized trial on supplemental MRI screening that has been performed in women with dense breasts.