Supplemental MRI screening for women with extremely dense breasts: results of three screening rounds of the DENSE trial
Author Block: S. V. Grinsven1, E. Monninkhof1, R. Mann2, W. B. Veldhuis1, C. Van Gils1, F. T. D. T. S. G. -1; 1Utrecht/NL, 2Nijmegen/NL
Purpose: To study the effect of supplemental MRI screening for women with extremely dense breasts on advanced breast cancers.
Methods or Background: Dutch women with extremely dense breasts and a negative mammogram were pre-randomized to either the MRI-invitation (n=8,061) or control group (n=32,312, standard mammography). In the first (prevalent) round, supplemental MRI led to higher cancer detection and fewer interval cancers. The rate of advanced breast cancers in subsequent (incident) screening rounds serves as a further important measure to assess the impact on health outcomes. Since many women randomized to MRI-invitation did not participate, intention-to-treat analyses dilute the true effect. Therefore, our main analysis is a per-protocol approach, comparing advanced breast cancer (TNM stage II+) rates, adjusted for age and socioeconomic status using inverse probability weighting. Rate differences (RD) were calculated with 95% confidence intervals.
Results or Findings: As expected, in the first round, the advanced breast cancer rate per 1000 women was similar between MRI participants and controls (RD: 0.8 [95% CI: -0.6, 2.2]). In the second round, the rate was lower in the MRI group but not yet statistically significant (RD: 1.4 [95% CI: -0.3, 3.2]). By the third round, the rate in the MRI group was significantly lower than in the control group (RD: 2.6 [95% CI: 0.9, 4.3]).
Conclusion: From the second round, MRI participants had lower advanced cancer rates, reaching significance in the third round. These findings show that the health benefits of MRI screening likely extend beyond lowering interval cancers.
Limitations: The primary outcome used a per-protocol and not an intention-to-treat approach. As mortality could not be studied due to limited sample size and follow-up, advanced breast cancer was used as a surrogate. These results will inform mortality modelling.
Funding for this study: Supported by the University Medical Center Utrecht (project number, UMCU DENSE), the Netherlands Organization for Health Research and Development (project numbers, ZonMW-200320002-UMCU and ZonMW Preventie 50-53125-98-014), the Dutch Cancer Society (project numbers, DCS-UU-2009-4348, UU-2014-6859, and UU-2014-7151), the Dutch Pink Ribbon–A Sister’s Hope (project number, Pink Ribbon-10074), Bayer Pharmaceuticals (project number, BSP-DENSE), and Stichting Kankerpreventie Midden-West. For research purposes, Volpara Health Technologies provided Volpara Imaging Software, version 1.5, for installation on servers in the screening units.
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: The Dutch Minister of Health, Welfare and Sport, who
was advised by the Health Council of the Netherlands
(2011/2019 WBO, The Hague, The Netherlands),
approved the DENSE trial on November 11, 2011.