Breast compression parameters and mammographic density in the Norwegian Breast Cancer Screening Programme.

Objectives: To investigate possible associations between breast compression parameters, including compression force, pressure and compressed breast thickness, and mammographic density assessed by an automated software.

Methods: We obtained data on breast compression parameters, breast volume, absolute and percentage dense volume, and body mass index for 14,698 women screened with two-view (craniocaudal, CC, and mediolateral oblique, MLO) digital mammography, in the Norwegian Breast Cancer Screening Programme, 2014-2015. The Spearman correlation coefficient (ρ) was used to measure correlation between breast compression parameters, breast volume and absolute and percentage dense volume. Linear regression was used to examine associations between breast compression parameters and absolute and percentage dense volume, adjusting for breast volume, age and BMI.

Results: A fair negative correlation was observed between compression pressure and absolute dense volume (ρ = - 0.37 for CC and ρ = - 0.34 for MLO). A moderate negative correlation was identified for compressed breast thickness and percentage dense volume (ρ = - 0.56 for CC and ρ = - 0.62 for MLO). These correlations were corroborated by the corresponding associations obtained in the adjusted regression analyses.

Conclusions: Results from this study indicate that breast compression parameters may influence absolute and percentage dense volume measured by the automated software.

Key Points: • A fair correlation was identified between compression pressure and absolute dense volume • A moderate correlation was identified between compressed breast thickness and percentage dense volume • Breast compression may influence automated density estimates.