In the Dutch DENSE study reported in The New England Journal of Medicine, Bakker et al found that supplemental magnetic resonance imaging (MRI) in women with extremely dense breast tissue and normal results on screening mammography was associated with the diagnosis of significantly fewer interval cancers vs mammography alone during a 2-year screening period.
“The use of supplemental MRI screening in women with extremely dense breast tissue and normal results on mammography resulted in the diagnosis of significantly fewer interval cancers than mammography alone during a 2-year screening period.”— Bakker et al
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Study Details
In the multicenter trial, 40,373 women aged 50 to 75 years with extremely dense breast tissue and normal results on screening mammography were randomly assigned 1:4 between December 2011 and November 2015 to invitation to supplemental MRI screening (n = 8,061) or mammography screening only (n = 32,312) during a 2-year screening period. The primary outcome measure was the between-group difference in incidence of interval cancers during the 2-year screening period.
In the MRI group, cancers were detected either on the screening MRI or at a 6-month repeat screening. Interval breast cancers included all those diagnosed after negative results on mammography and before the next scheduled mammography.
Key Findings
Interval cancer rates were 2.5 per 1,000 screenings in the MRI-invitation group vs 5.0 per 1,000 screenings in the mammography-only group, yielding a difference of 2.5 per 1,000 screenings (95% confidence interval [CI] = 1.0–3.7, P < .001).
About 59% of women in the MRI-invitation group accepted the invitation and underwent MRI screening. Of 20 interval cancers diagnosed in the MRI-invitation group, 4 were in the women who underwent MRI (0.8 per 1,000 screenings) and 16 were in women who did not accept the invitation (4.9 per 1,000 screenings). The MRI cancer detection rate among women who underwent MRI screening was 16.5 per 1,000 screenings.
The positive predictive value of a positive MRI result was 17.4% for recall for additional testing and 23.9% for indication for biopsy. The positive predictive value of biopsy was 26.3%.
The false-positive rate for MRI was 79.8 per 1,000 screenings. On the basis of MRI findings, 300 women underwent biopsy; among them, 79 were diagnosed with breast cancer, including 64 with invasive disease and 15 with ductal carcinoma in situ. Among women who underwent MRI, 0.1% had an adverse event during or immediately after screening (vasovagal response, contrast reaction, or intravenous line infiltration).
The investigators concluded, “The use of supplemental MRI screening in women with extremely dense breast tissue and normal results on mammography resulted in the diagnosis of significantly fewer interval cancers than mammography alone during a 2-year screening period.”
Disclosure: The study was funded by the University Medical Center Utrecht and others. For full disclosures of the study authors, visit nejm.org.
