Supplemental MRI screening an option for women with extremely dense breast tissue

29 Feb 2020

Breast cancer is the most common cancer amongst females in Hong Kong, accounting for 26.6% of all new cancers in females diagnosed in 2016.1 Women with extremely dense breast tissue have an increased risk of breast cancer, which is also associated with decreased mammographic sensitivity and specificity.2 The DENSE trial was a randomized controlled trial that found the supplemental magnetic resonance imaging (MRI) in women with extremely dense breast tissue resulted in the diagnosis of significantly fewer interval cancers than mammography alone.3 The results of the first 2-year screening round were recently published in The New England Journal of Medicine.3

Dense breasts are defined by mammographic appearance.2 It is estimated that 43% of women aged 40 to 74 years in the United States (U.S.) have dense breasts.2 These patients may benefit from a tailored breast cancer screening strategy that is supplemented with more sensitive imaging methods.3 Supplemental imaging would increase the rate of cancer detection in women with dense breasts, but it remains to be seen if it would improve the health outcomes.3

The DENSE trial was a randomized, multicenter and controlled trial that aimed to investigate the effect of supplemental MRI on the incidence of interval cancers in women with extremely dense breast tissue.3 40,373 women who were participating in the Dutch population-based digital mammography screening program between age 50 and 75 years were randomly assigned in a 1:4 ratio to undergo supplemental MRI or mammography screening only.3 The primary outcome was the between-group difference in the incidence of interval cancers.3 Key secondary outcomes included the recall rate for additional examination, cancer-detection rate on MRI, false positive rate, positive predictive value, and tumor characteristics.3

The interval-cancer rate in the supplemental MRI group was 2.5 per 1,000 screenings (95% CI: 1.6-3.8) and 5.0 per 1,000 screenings (95% CI: 4.3-5.8) in the mammography-only group.3 In the intention-to-screen analysis, the interval-cancer rate was lower by 2.5 per 1,000 screenings (95% CI: 1.0-3.7; p<0.001) in the supplemental MRI group than in the mammography-only group.3 The positive predictive value of a positive MRI result and indication for biopsy was 17.4% and 23.9%, respectively. MRI screening had a specificity of 92%, and as a result of the MRI, 300 women underwent a breast biopsy.3 Of these women, breast cancer was diagnosed in 79.3 The program sensitivity of MRI screening was 95.2%.3 The screening-detected tumors were smaller on average than of those in other groups.3

Supplemental MRI screening led to a significantly lower interval-cancer rate than with mammography alone. As women with high-density breast tissue face two major challenges, late diagnosis of breast cancer due to poor sensitivity of mammographic screening, and higher risk of developing breast cancer.4 However, currently no clinical guidelines explicitly recommend the use of supplemental breast cancer screening on women with dense breasts.2 Future avenues should evaluate methods for minimizing false positive outcomes, and validating abbreviated MRI protocols to reduce the costs of MRI screening.3

  1. Centre for Health Protection - Breast Cancer. Breast cancer. Published April 8, 2019. Accessed January 8, 2020.
  2. Melnikow J, Fenton JJ, Whitlock EP, et al. Supplemental Screening for Breast Cancer in Women with Dense Breasts: A Systematic Review for the U.S. Preventive Services Task Force. Annals of internal medicine. 2016;164(4):268. doi:10.7326/M15-1789
  3. Bakker MF, de Lange SV, Pijnappel RM, et al. Supplemental MRI Screening for Women with Extremely Dense Breast Tissue. N Engl J Med. 2019;381(22):2091-2102. doi:10.1056/NEJMoa1903986
  4. Nazari SS, Mukherjee P. An overview of mammographic density and its association with breast cancer. Breast Cancer (Tokyo, Japan). 2018;25(3):259. doi:10.1007/s12282-018-0857-5
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